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Wendy M. Schluchter - One of the best experts on this subject based on the ideXlab platform.
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MpeV is a lyase isomerase that ligates a doubly-linked phycourobilin on the β-subunit of phycoerythrin I and II in marine Synechococcus.
The Journal of biological chemistry, 2020Co-Authors: Lyndsay A. Carrigee, Frédéric Partensky, Laurence Garczarek, Jacob P. Frick, Jonathan A. Karty, Wendy M. SchluchterAbstract:Synechococcus cyanobacteria are widespread in the marine environment, as the extensive pigment diversity within their light-harvesting phycobilisomes enables them to utilize various wavelengths of light for photosynthesis. The phycobilisomes of Synechococcus sp. RS9916 contain two forms of the protein phycoerythrin (PEI and PEII), each binding two chromophores, green-light absorbing Phycoerythrobilin and blue-light absorbing phycourobilin. These chromophores are ligated to specific cysteines via bilin lyases, and some of these enzymes, called lyase isomerases, attach Phycoerythrobilin and simultaneously isomerize it to phycourobilin. MpeV is a putative lyase isomerase whose role in PEI and PEII biosynthesis is not clear. We examined MpeV in RS9916 using recombinant protein expression, absorbance spectroscopy, and tandem mass spectrometry. Our results show that MpeV is the lyase isomerase that covalently attaches a doubly linked phycourobilin to two cysteine residues (C50, C61) on the β-subunit of both PEI (CpeB) and PEII (MpeB). MpeV activity requires that CpeB or MpeB is first chromophorylated by the lyase CpeS (which adds Phycoerythrobilin to C82). Its activity is further enhanced by CpeZ (a homolog of a chaperone-like protein first characterized in Fremyella diplosiphon). MpeV showed no detectable activity on the α-subunits of PEI or PEII. The mechanism by which MpeV links the A and D rings of phycourobilin to C50 and C61 of CpeB was also explored using site-directed mutants, revealing that linkage at the A ring to C50 is a critical step in chromophore attachment, isomerization, and stability. These data provide novel insights into β-PE biosynthesis and advance our understanding of the mechanisms guiding lyase isomerases.
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CpeY is a Phycoerythrobilin lyase for cysteine 82 of the phycoerythrin I α-subunit in marine Synechococcus.
Biochimica et biophysica acta. Bioenergetics, 2020Co-Authors: Lyndsay A. Carrigee, David M. Kehoe, Rania M. Mahmoud, Joseph E. Sanfilippo, Johann A. Strnat, Jacob P. Frick, Jonathan A. Karty, Bo Chen, Wendy M. SchluchterAbstract:Abstract Marine Synechococcus are widespread in part because they are efficient at harvesting available light using their complex antenna, or phycobilisome, composed of multiple phycobiliproteins and bilin chromophores. Over 40% of Synechococcus strains are predicted to perform a type of chromatic acclimation that alters the ratio of two chromophores, green-light–absorbing Phycoerythrobilin and blue-light–absorbing phycourobilin, to optimize light capture by phycoerythrin in the phycobilisome. Lyases are enzymes which catalyze the addition of bilin chromophores to specific cysteine residues on phycobiliproteins and are involved in chromatic acclimation. CpeY, a candidate lyase in the model strain Synechococcus sp. RS9916, added Phycoerythrobilin to cysteine 82 of only the α subunit of phycoerythrin I (CpeA) in the presence or absence of the chaperone-like protein CpeZ in a recombinant protein expression system. These studies demonstrated that recombinant CpeY attaches Phycoerythrobilin to as much as 72% of CpeA, making it one of the most efficient phycoerythrin lyases characterized to date. Phycobilisomes from a cpeY− mutant showed a near native bilin composition in all light conditions except for a slight replacement of Phycoerythrobilin by phycourobilin at CpeA cysteine 82. This demonstrates that CpeY is not involved in any chromatic acclimation-driven chromophore changes and suggests that the chromophore attached at cysteine 82 of CpeA in the cpeY− mutant is ligated by an alternative Phycoerythrobilin lyase. Although loss of CpeY does not greatly inhibit native phycobilisome assembly in vivo, the highly active recombinant CpeY can be used to generate large amounts of fluorescent CpeA for biotechnological uses.
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The roles of the chaperone-like protein CpeZ and the Phycoerythrobilin lyase CpeY in phycoerythrin biogenesis.
Biochimica et biophysica acta. Bioenergetics, 2019Co-Authors: Christina M Kronfel, Avijit Biswas, David M. Kehoe, Jacob P. Frick, Jonathan A. Karty, Andrian Gutu, Tyler Blensdorf, Wendy M. SchluchterAbstract:Phycoerythrin (PE) present in the distal ends of light-harvesting phycobilisome rods in Fremyella diplosiphon (Tolypothrix sp. PCC 7601) contains five Phycoerythrobilin (PEB) chromophores attached to six cysteine residues for efficient green light capture for photosynthesis. Chromophore ligation on PE subunits occurs through bilin lyase catalyzed reactions, but the characterization of the roles of all bilin lyases for phycoerythrin is not yet complete. To gain a more complete understanding about the individual functions of CpeZ and CpeY in PE biogenesis in cyanobacteria, we examined PE and phycobilisomes purified from wild type F. diplosiphon, cpeZ and cpeY knockout mutants. We find that the cpeZ and cpeY mutants accumulate less PE than wild type cells. We show that in the cpeZ mutant, chromophorylation of both PE subunits is affected, especially the Cys-80 and Cys-48/Cys-59 sites of CpeB, the beta-subunit of PE. The cpeY mutant showed reduced chromophorylation at Cys-82 of CpeA. We also show that, in vitro, CpeZ stabilizes PE subunits and assists in refolding of CpeB after denaturation. Taken together, we conclude that CpeZ acts as a chaperone-like protein, assisting in the folding/stability of PE subunits, allowing bilin lyases such as CpeY and CpeS to attach PEB to their PE subunit.
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Adaptation to Blue Light in Marine Synechococcus Requires MpeU, an Enzyme with Similarity to Phycoerythrobilin Lyase Isomerases
Frontiers in Microbiology, 2017Co-Authors: Rania M. Mahmoud, David M. Kehoe, Joseph E. Sanfilippo, Adam A. Nguyen, Johann A. Strnat, Frédéric Partensky, Laurence Garczarek, Nabil Abo El Kassem, Wendy M. SchluchterAbstract:Marine Synechococcus has successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant group of microorganisms worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here, we show that all Synechococcus strains adapted to blue light possess a gene called mpeU. MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, impaired phycobilisome assembly and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU-less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a Phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world’s oceans.
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adaptation to blue light in marine synechococcus requires mpeu an enzyme with similarity to Phycoerythrobilin lyase isomerases
Frontiers in Microbiology, 2017Co-Authors: Rania M. Mahmoud, David M. Kehoe, Joseph E. Sanfilippo, Adam A. Nguyen, Johann A. Strnat, Frédéric Partensky, Laurence Garczarek, Nabil Abo El Kassem, Wendy M. SchluchterAbstract:Marine Synechococcus cyanobacteria have successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant photosynthetic microorganism worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here we show that all Synechococcus strains adapted to blue light possess a gene called mpeU. MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, produced impaired phycobilisomes and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU-less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a Phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world’s oceans.
Frédéric Partensky - One of the best experts on this subject based on the ideXlab platform.
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MpeV is a lyase isomerase that ligates a doubly-linked phycourobilin on the β-subunit of phycoerythrin I and II in marine Synechococcus.
The Journal of biological chemistry, 2020Co-Authors: Lyndsay A. Carrigee, Frédéric Partensky, Laurence Garczarek, Jacob P. Frick, Jonathan A. Karty, Wendy M. SchluchterAbstract:Synechococcus cyanobacteria are widespread in the marine environment, as the extensive pigment diversity within their light-harvesting phycobilisomes enables them to utilize various wavelengths of light for photosynthesis. The phycobilisomes of Synechococcus sp. RS9916 contain two forms of the protein phycoerythrin (PEI and PEII), each binding two chromophores, green-light absorbing Phycoerythrobilin and blue-light absorbing phycourobilin. These chromophores are ligated to specific cysteines via bilin lyases, and some of these enzymes, called lyase isomerases, attach Phycoerythrobilin and simultaneously isomerize it to phycourobilin. MpeV is a putative lyase isomerase whose role in PEI and PEII biosynthesis is not clear. We examined MpeV in RS9916 using recombinant protein expression, absorbance spectroscopy, and tandem mass spectrometry. Our results show that MpeV is the lyase isomerase that covalently attaches a doubly linked phycourobilin to two cysteine residues (C50, C61) on the β-subunit of both PEI (CpeB) and PEII (MpeB). MpeV activity requires that CpeB or MpeB is first chromophorylated by the lyase CpeS (which adds Phycoerythrobilin to C82). Its activity is further enhanced by CpeZ (a homolog of a chaperone-like protein first characterized in Fremyella diplosiphon). MpeV showed no detectable activity on the α-subunits of PEI or PEII. The mechanism by which MpeV links the A and D rings of phycourobilin to C50 and C61 of CpeB was also explored using site-directed mutants, revealing that linkage at the A ring to C50 is a critical step in chromophore attachment, isomerization, and stability. These data provide novel insights into β-PE biosynthesis and advance our understanding of the mechanisms guiding lyase isomerases.
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Adaptation to Blue Light in Marine Synechococcus Requires MpeU, an Enzyme with Similarity to Phycoerythrobilin Lyase Isomerases
Frontiers in Microbiology, 2017Co-Authors: Rania M. Mahmoud, David M. Kehoe, Joseph E. Sanfilippo, Adam A. Nguyen, Johann A. Strnat, Frédéric Partensky, Laurence Garczarek, Nabil Abo El Kassem, Wendy M. SchluchterAbstract:Marine Synechococcus has successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant group of microorganisms worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here, we show that all Synechococcus strains adapted to blue light possess a gene called mpeU. MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, impaired phycobilisome assembly and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU-less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a Phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world’s oceans.
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adaptation to blue light in marine synechococcus requires mpeu an enzyme with similarity to Phycoerythrobilin lyase isomerases
Frontiers in Microbiology, 2017Co-Authors: Rania M. Mahmoud, David M. Kehoe, Joseph E. Sanfilippo, Adam A. Nguyen, Johann A. Strnat, Frédéric Partensky, Laurence Garczarek, Nabil Abo El Kassem, Wendy M. SchluchterAbstract:Marine Synechococcus cyanobacteria have successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant photosynthetic microorganism worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here we show that all Synechococcus strains adapted to blue light possess a gene called mpeU. MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, produced impaired phycobilisomes and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU-less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a Phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world’s oceans.
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phylogeography and pigment type diversity of synechococcus cyanobacteria in surface waters of the northwestern pacific ocean
Environmental Microbiology, 2017Co-Authors: Frédéric Partensky, Laurence Garczarek, Koji Suzuki, Shunyan CheungAbstract:The widespread unicellular cyanobacteria Synechococcus are major contributors to global marine primary production. Here we report their abundance, phylogenetic diversity (as assessed using the RNA polymerase gamma subunit gene rpoC1) and pigment diversity (as indirectly assessed using the laterally transferred cpeBA genes, encoding phycoerythrin-I) in surface waters of the northwestern Pacific Ocean, sampled over nine distinct cruises (2008-2015). Abundance of Synechococcus was low in the subarctic ocean and South China Sea, intermediate in the western subtropical Pacific Ocean, and the highest in the Japan and East China seas. Clades I and II were by far the most abundant Synechococcus lineages, the former dominating in temperate cold waters and the latter in (sub)tropical waters. Clades III and VI were also fairly abundant in warm waters, but with a narrower distribution than clade II. One type of chromatic acclimater (3dA) largely dominated the Synechococcus communities in the subarctic ocean, while another (3dB) and/or cells with a fixed high phycourobilin to Phycoerythrobilin ratio (pigment type 3c) predominated at mid and low latitudes. Altogether, our results suggest that the variety of pigment content found in most Synechococcus clades considerably extends the niches that they can colonize and therefore the whole genus habitat.
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A Gene Island with Two Possible Configurations Is Involved in Chromatic Acclimation in Marine Synechococcus
PLoS ONE, 2013Co-Authors: Florian Humily, Frédéric Partensky, Morgane Ratin, Christophe Six, Gregory K. Farrant, Dominique Marie, Laurence GarczarekAbstract:Synechococcus, the second most abundant oxygenic phototroph in the marine environment, harbors the largest pigment diversity known within a single genus of cyanobacteria, allowing it to exploit a wide range of light niches. Some strains are capable of Type IV chromatic acclimation (CA4), a process by which cells can match the phycobilin content of their phycobilisomes to the ambient light quality. Here, we performed extensive genomic comparisons to explore the diversity of this process within the marine Synechococcus radiation. A specific gene island was identified in all CA4-performing strains, containing two genes (fciA/b) coding for possible transcriptional regulators and one gene coding for a phycobilin lyase. However, two distinct configurations of this cluster were observed, depending on the lineage. CA4-A islands contain the mpeZ gene, encoding a recently characterized Phycoerythrobilin lyase-isomerase, and a third, small, possible regulator called fciC. In CA4-B islands, the lyase gene encodes an uncharacterized relative of MpeZ, called MpeW. While mpeZ is expressed more in blue light than green light, this is the reverse for mpeW, although only small phenotypic differences were found among chromatic acclimaters possessing either CA4 island type. This study provides novel insights into understanding both diversity and evolution of the CA4 process.
David M. Kehoe - One of the best experts on this subject based on the ideXlab platform.
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CpeY is a Phycoerythrobilin lyase for cysteine 82 of the phycoerythrin I α-subunit in marine Synechococcus.
Biochimica et biophysica acta. Bioenergetics, 2020Co-Authors: Lyndsay A. Carrigee, David M. Kehoe, Rania M. Mahmoud, Joseph E. Sanfilippo, Johann A. Strnat, Jacob P. Frick, Jonathan A. Karty, Bo Chen, Wendy M. SchluchterAbstract:Abstract Marine Synechococcus are widespread in part because they are efficient at harvesting available light using their complex antenna, or phycobilisome, composed of multiple phycobiliproteins and bilin chromophores. Over 40% of Synechococcus strains are predicted to perform a type of chromatic acclimation that alters the ratio of two chromophores, green-light–absorbing Phycoerythrobilin and blue-light–absorbing phycourobilin, to optimize light capture by phycoerythrin in the phycobilisome. Lyases are enzymes which catalyze the addition of bilin chromophores to specific cysteine residues on phycobiliproteins and are involved in chromatic acclimation. CpeY, a candidate lyase in the model strain Synechococcus sp. RS9916, added Phycoerythrobilin to cysteine 82 of only the α subunit of phycoerythrin I (CpeA) in the presence or absence of the chaperone-like protein CpeZ in a recombinant protein expression system. These studies demonstrated that recombinant CpeY attaches Phycoerythrobilin to as much as 72% of CpeA, making it one of the most efficient phycoerythrin lyases characterized to date. Phycobilisomes from a cpeY− mutant showed a near native bilin composition in all light conditions except for a slight replacement of Phycoerythrobilin by phycourobilin at CpeA cysteine 82. This demonstrates that CpeY is not involved in any chromatic acclimation-driven chromophore changes and suggests that the chromophore attached at cysteine 82 of CpeA in the cpeY− mutant is ligated by an alternative Phycoerythrobilin lyase. Although loss of CpeY does not greatly inhibit native phycobilisome assembly in vivo, the highly active recombinant CpeY can be used to generate large amounts of fluorescent CpeA for biotechnological uses.
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The roles of the chaperone-like protein CpeZ and the Phycoerythrobilin lyase CpeY in phycoerythrin biogenesis.
Biochimica et biophysica acta. Bioenergetics, 2019Co-Authors: Christina M Kronfel, Avijit Biswas, David M. Kehoe, Jacob P. Frick, Jonathan A. Karty, Andrian Gutu, Tyler Blensdorf, Wendy M. SchluchterAbstract:Phycoerythrin (PE) present in the distal ends of light-harvesting phycobilisome rods in Fremyella diplosiphon (Tolypothrix sp. PCC 7601) contains five Phycoerythrobilin (PEB) chromophores attached to six cysteine residues for efficient green light capture for photosynthesis. Chromophore ligation on PE subunits occurs through bilin lyase catalyzed reactions, but the characterization of the roles of all bilin lyases for phycoerythrin is not yet complete. To gain a more complete understanding about the individual functions of CpeZ and CpeY in PE biogenesis in cyanobacteria, we examined PE and phycobilisomes purified from wild type F. diplosiphon, cpeZ and cpeY knockout mutants. We find that the cpeZ and cpeY mutants accumulate less PE than wild type cells. We show that in the cpeZ mutant, chromophorylation of both PE subunits is affected, especially the Cys-80 and Cys-48/Cys-59 sites of CpeB, the beta-subunit of PE. The cpeY mutant showed reduced chromophorylation at Cys-82 of CpeA. We also show that, in vitro, CpeZ stabilizes PE subunits and assists in refolding of CpeB after denaturation. Taken together, we conclude that CpeZ acts as a chaperone-like protein, assisting in the folding/stability of PE subunits, allowing bilin lyases such as CpeY and CpeS to attach PEB to their PE subunit.
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Adaptation to Blue Light in Marine Synechococcus Requires MpeU, an Enzyme with Similarity to Phycoerythrobilin Lyase Isomerases
Frontiers in Microbiology, 2017Co-Authors: Rania M. Mahmoud, David M. Kehoe, Joseph E. Sanfilippo, Adam A. Nguyen, Johann A. Strnat, Frédéric Partensky, Laurence Garczarek, Nabil Abo El Kassem, Wendy M. SchluchterAbstract:Marine Synechococcus has successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant group of microorganisms worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here, we show that all Synechococcus strains adapted to blue light possess a gene called mpeU. MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, impaired phycobilisome assembly and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU-less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a Phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world’s oceans.
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adaptation to blue light in marine synechococcus requires mpeu an enzyme with similarity to Phycoerythrobilin lyase isomerases
Frontiers in Microbiology, 2017Co-Authors: Rania M. Mahmoud, David M. Kehoe, Joseph E. Sanfilippo, Adam A. Nguyen, Johann A. Strnat, Frédéric Partensky, Laurence Garczarek, Nabil Abo El Kassem, Wendy M. SchluchterAbstract:Marine Synechococcus cyanobacteria have successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant photosynthetic microorganism worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here we show that all Synechococcus strains adapted to blue light possess a gene called mpeU. MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, produced impaired phycobilisomes and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU-less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a Phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world’s oceans.
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Phycoerythrin-specific bilin lyase-isomerase controls blue-green chromatic acclimation in marine Synechococcus.
Proceedings of the National Academy of Sciences of the United States of America, 2012Co-Authors: Animesh Shukla, Avijit Biswas, Frédéric Partensky, Laurence Garczarek, Wendy M. Schluchter, Jonathan A. Karty, Nicolas Blot, Loubna A Hammad, Andrian Gutu, David M. KehoeAbstract:The marine cyanobacterium Synechococcus is the second most abundant phytoplanktonic organism in the world's oceans. The ubiquity of this genus is in large part due to its use of a diverse set of photosynthetic light-harvesting pigments called phycobiliproteins, which allow it to efficiently exploit a wide range of light colors. Here we uncover a pivotal molecular mechanism underpinning a widespread response among marine Synechococcus cells known as "type IV chromatic acclimation" (CA4). During this process, the pigmentation of the two main phycobiliproteins of this organism, phycoerythrins I and II, is reversibly modified to match changes in the ambient light color so as to maximize photon capture for photosynthesis. CA4 involves the replacement of three molecules of the green light-absorbing chromophore Phycoerythrobilin with an equivalent number of the blue light-absorbing chromophore phycourobilin when cells are shifted from green to blue light, and the reverse after a shift from blue to green light. We have identified and characterized MpeZ, an enzyme critical for CA4 in marine Synechococcus. MpeZ attaches Phycoerythrobilin to cysteine-83 of the α-subunit of phycoerythrin II and isomerizes it to phycourobilin. mpeZ RNA is six times more abundant in blue light, suggesting that its proper regulation is critical for CA4. Furthermore, mpeZ mutants fail to normally acclimate in blue light. These findings provide insights into the molecular mechanisms controlling an ecologically important photosynthetic process and identify a unique class of phycoerythrin lyase/isomerases, which will further expand the already widespread use of phycoerythrin in biotechnology and cell biology applications.
Laurence Garczarek - One of the best experts on this subject based on the ideXlab platform.
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MpeV is a lyase isomerase that ligates a doubly-linked phycourobilin on the β-subunit of phycoerythrin I and II in marine Synechococcus.
The Journal of biological chemistry, 2020Co-Authors: Lyndsay A. Carrigee, Frédéric Partensky, Laurence Garczarek, Jacob P. Frick, Jonathan A. Karty, Wendy M. SchluchterAbstract:Synechococcus cyanobacteria are widespread in the marine environment, as the extensive pigment diversity within their light-harvesting phycobilisomes enables them to utilize various wavelengths of light for photosynthesis. The phycobilisomes of Synechococcus sp. RS9916 contain two forms of the protein phycoerythrin (PEI and PEII), each binding two chromophores, green-light absorbing Phycoerythrobilin and blue-light absorbing phycourobilin. These chromophores are ligated to specific cysteines via bilin lyases, and some of these enzymes, called lyase isomerases, attach Phycoerythrobilin and simultaneously isomerize it to phycourobilin. MpeV is a putative lyase isomerase whose role in PEI and PEII biosynthesis is not clear. We examined MpeV in RS9916 using recombinant protein expression, absorbance spectroscopy, and tandem mass spectrometry. Our results show that MpeV is the lyase isomerase that covalently attaches a doubly linked phycourobilin to two cysteine residues (C50, C61) on the β-subunit of both PEI (CpeB) and PEII (MpeB). MpeV activity requires that CpeB or MpeB is first chromophorylated by the lyase CpeS (which adds Phycoerythrobilin to C82). Its activity is further enhanced by CpeZ (a homolog of a chaperone-like protein first characterized in Fremyella diplosiphon). MpeV showed no detectable activity on the α-subunits of PEI or PEII. The mechanism by which MpeV links the A and D rings of phycourobilin to C50 and C61 of CpeB was also explored using site-directed mutants, revealing that linkage at the A ring to C50 is a critical step in chromophore attachment, isomerization, and stability. These data provide novel insights into β-PE biosynthesis and advance our understanding of the mechanisms guiding lyase isomerases.
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Adaptation to Blue Light in Marine Synechococcus Requires MpeU, an Enzyme with Similarity to Phycoerythrobilin Lyase Isomerases
Frontiers in Microbiology, 2017Co-Authors: Rania M. Mahmoud, David M. Kehoe, Joseph E. Sanfilippo, Adam A. Nguyen, Johann A. Strnat, Frédéric Partensky, Laurence Garczarek, Nabil Abo El Kassem, Wendy M. SchluchterAbstract:Marine Synechococcus has successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant group of microorganisms worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here, we show that all Synechococcus strains adapted to blue light possess a gene called mpeU. MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, impaired phycobilisome assembly and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU-less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a Phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world’s oceans.
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adaptation to blue light in marine synechococcus requires mpeu an enzyme with similarity to Phycoerythrobilin lyase isomerases
Frontiers in Microbiology, 2017Co-Authors: Rania M. Mahmoud, David M. Kehoe, Joseph E. Sanfilippo, Adam A. Nguyen, Johann A. Strnat, Frédéric Partensky, Laurence Garczarek, Nabil Abo El Kassem, Wendy M. SchluchterAbstract:Marine Synechococcus cyanobacteria have successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant photosynthetic microorganism worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here we show that all Synechococcus strains adapted to blue light possess a gene called mpeU. MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, produced impaired phycobilisomes and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU-less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a Phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world’s oceans.
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phylogeography and pigment type diversity of synechococcus cyanobacteria in surface waters of the northwestern pacific ocean
Environmental Microbiology, 2017Co-Authors: Frédéric Partensky, Laurence Garczarek, Koji Suzuki, Shunyan CheungAbstract:The widespread unicellular cyanobacteria Synechococcus are major contributors to global marine primary production. Here we report their abundance, phylogenetic diversity (as assessed using the RNA polymerase gamma subunit gene rpoC1) and pigment diversity (as indirectly assessed using the laterally transferred cpeBA genes, encoding phycoerythrin-I) in surface waters of the northwestern Pacific Ocean, sampled over nine distinct cruises (2008-2015). Abundance of Synechococcus was low in the subarctic ocean and South China Sea, intermediate in the western subtropical Pacific Ocean, and the highest in the Japan and East China seas. Clades I and II were by far the most abundant Synechococcus lineages, the former dominating in temperate cold waters and the latter in (sub)tropical waters. Clades III and VI were also fairly abundant in warm waters, but with a narrower distribution than clade II. One type of chromatic acclimater (3dA) largely dominated the Synechococcus communities in the subarctic ocean, while another (3dB) and/or cells with a fixed high phycourobilin to Phycoerythrobilin ratio (pigment type 3c) predominated at mid and low latitudes. Altogether, our results suggest that the variety of pigment content found in most Synechococcus clades considerably extends the niches that they can colonize and therefore the whole genus habitat.
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A Gene Island with Two Possible Configurations Is Involved in Chromatic Acclimation in Marine Synechococcus
PLoS ONE, 2013Co-Authors: Florian Humily, Frédéric Partensky, Morgane Ratin, Christophe Six, Gregory K. Farrant, Dominique Marie, Laurence GarczarekAbstract:Synechococcus, the second most abundant oxygenic phototroph in the marine environment, harbors the largest pigment diversity known within a single genus of cyanobacteria, allowing it to exploit a wide range of light niches. Some strains are capable of Type IV chromatic acclimation (CA4), a process by which cells can match the phycobilin content of their phycobilisomes to the ambient light quality. Here, we performed extensive genomic comparisons to explore the diversity of this process within the marine Synechococcus radiation. A specific gene island was identified in all CA4-performing strains, containing two genes (fciA/b) coding for possible transcriptional regulators and one gene coding for a phycobilin lyase. However, two distinct configurations of this cluster were observed, depending on the lineage. CA4-A islands contain the mpeZ gene, encoding a recently characterized Phycoerythrobilin lyase-isomerase, and a third, small, possible regulator called fciC. In CA4-B islands, the lyase gene encodes an uncharacterized relative of MpeZ, called MpeW. While mpeZ is expressed more in blue light than green light, this is the reverse for mpeW, although only small phenotypic differences were found among chromatic acclimaters possessing either CA4 island type. This study provides novel insights into understanding both diversity and evolution of the CA4 process.
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molecular bases of an alternative dual enzyme system for light color acclimation of marine synechococcus cyanobacteria
Proceedings of the National Academy of Sciences of the United States of America, 2021Co-Authors: Adam A. Nguyen, Jonathan A. Karty, Bo Chen, Theophile Grebert, Suman Pokhrel, Kes Lynn Joseph, Morgane Ratin, Louison Dufour, Allissa M Haney, Jonathan C TrinidadAbstract:Marine Synechococcus cyanobacteria owe their ubiquity in part to the wide pigment diversity of their light-harvesting complexes. In open ocean waters, cells predominantly possess sophisticated antennae with rods composed of phycocyanin and two types of phycoerythrins (PEI and PEII). Some strains are specialized for harvesting either green or blue light, while others can dynamically modify their light absorption spectrum to match the dominant ambient color. This process, called type IV chromatic acclimation (CA4), has been linked to the presence of a small genomic island occurring in two configurations (CA4-A and CA4-B). While the CA4-A process has been partially characterized, the CA4-B process has remained an enigma. Here we characterize the function of two members of the phycobilin lyase E/F clan, MpeW and MpeQ, in Synechococcus sp. strain A15-62 and demonstrate their critical role in CA4-B. While MpeW, encoded in the CA4-B island and up-regulated in green light, attaches the green light-absorbing chromophore Phycoerythrobilin to cysteine-83 of the PEII α-subunit in green light, MpeQ binds Phycoerythrobilin and isomerizes it into the blue light-absorbing phycourobilin at the same site in blue light, reversing the relationship of MpeZ and MpeY in the CA4-A strain RS9916. Our data thus reveal key molecular differences between the two types of chromatic acclimaters, both highly abundant but occupying distinct complementary ecological niches in the ocean. They also support an evolutionary scenario whereby CA4-B island acquisition allowed former blue light specialists to become chromatic acclimaters, while former green light specialists would have acquired this capacity by gaining a CA4-A island.
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MpeV is a lyase isomerase that ligates a doubly-linked phycourobilin on the β-subunit of phycoerythrin I and II in marine Synechococcus.
The Journal of biological chemistry, 2020Co-Authors: Lyndsay A. Carrigee, Frédéric Partensky, Laurence Garczarek, Jacob P. Frick, Jonathan A. Karty, Wendy M. SchluchterAbstract:Synechococcus cyanobacteria are widespread in the marine environment, as the extensive pigment diversity within their light-harvesting phycobilisomes enables them to utilize various wavelengths of light for photosynthesis. The phycobilisomes of Synechococcus sp. RS9916 contain two forms of the protein phycoerythrin (PEI and PEII), each binding two chromophores, green-light absorbing Phycoerythrobilin and blue-light absorbing phycourobilin. These chromophores are ligated to specific cysteines via bilin lyases, and some of these enzymes, called lyase isomerases, attach Phycoerythrobilin and simultaneously isomerize it to phycourobilin. MpeV is a putative lyase isomerase whose role in PEI and PEII biosynthesis is not clear. We examined MpeV in RS9916 using recombinant protein expression, absorbance spectroscopy, and tandem mass spectrometry. Our results show that MpeV is the lyase isomerase that covalently attaches a doubly linked phycourobilin to two cysteine residues (C50, C61) on the β-subunit of both PEI (CpeB) and PEII (MpeB). MpeV activity requires that CpeB or MpeB is first chromophorylated by the lyase CpeS (which adds Phycoerythrobilin to C82). Its activity is further enhanced by CpeZ (a homolog of a chaperone-like protein first characterized in Fremyella diplosiphon). MpeV showed no detectable activity on the α-subunits of PEI or PEII. The mechanism by which MpeV links the A and D rings of phycourobilin to C50 and C61 of CpeB was also explored using site-directed mutants, revealing that linkage at the A ring to C50 is a critical step in chromophore attachment, isomerization, and stability. These data provide novel insights into β-PE biosynthesis and advance our understanding of the mechanisms guiding lyase isomerases.
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CpeY is a Phycoerythrobilin lyase for cysteine 82 of the phycoerythrin I α-subunit in marine Synechococcus.
Biochimica et biophysica acta. Bioenergetics, 2020Co-Authors: Lyndsay A. Carrigee, David M. Kehoe, Rania M. Mahmoud, Joseph E. Sanfilippo, Johann A. Strnat, Jacob P. Frick, Jonathan A. Karty, Bo Chen, Wendy M. SchluchterAbstract:Abstract Marine Synechococcus are widespread in part because they are efficient at harvesting available light using their complex antenna, or phycobilisome, composed of multiple phycobiliproteins and bilin chromophores. Over 40% of Synechococcus strains are predicted to perform a type of chromatic acclimation that alters the ratio of two chromophores, green-light–absorbing Phycoerythrobilin and blue-light–absorbing phycourobilin, to optimize light capture by phycoerythrin in the phycobilisome. Lyases are enzymes which catalyze the addition of bilin chromophores to specific cysteine residues on phycobiliproteins and are involved in chromatic acclimation. CpeY, a candidate lyase in the model strain Synechococcus sp. RS9916, added Phycoerythrobilin to cysteine 82 of only the α subunit of phycoerythrin I (CpeA) in the presence or absence of the chaperone-like protein CpeZ in a recombinant protein expression system. These studies demonstrated that recombinant CpeY attaches Phycoerythrobilin to as much as 72% of CpeA, making it one of the most efficient phycoerythrin lyases characterized to date. Phycobilisomes from a cpeY− mutant showed a near native bilin composition in all light conditions except for a slight replacement of Phycoerythrobilin by phycourobilin at CpeA cysteine 82. This demonstrates that CpeY is not involved in any chromatic acclimation-driven chromophore changes and suggests that the chromophore attached at cysteine 82 of CpeA in the cpeY− mutant is ligated by an alternative Phycoerythrobilin lyase. Although loss of CpeY does not greatly inhibit native phycobilisome assembly in vivo, the highly active recombinant CpeY can be used to generate large amounts of fluorescent CpeA for biotechnological uses.
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The roles of the chaperone-like protein CpeZ and the Phycoerythrobilin lyase CpeY in phycoerythrin biogenesis.
Biochimica et biophysica acta. Bioenergetics, 2019Co-Authors: Christina M Kronfel, Avijit Biswas, David M. Kehoe, Jacob P. Frick, Jonathan A. Karty, Andrian Gutu, Tyler Blensdorf, Wendy M. SchluchterAbstract:Phycoerythrin (PE) present in the distal ends of light-harvesting phycobilisome rods in Fremyella diplosiphon (Tolypothrix sp. PCC 7601) contains five Phycoerythrobilin (PEB) chromophores attached to six cysteine residues for efficient green light capture for photosynthesis. Chromophore ligation on PE subunits occurs through bilin lyase catalyzed reactions, but the characterization of the roles of all bilin lyases for phycoerythrin is not yet complete. To gain a more complete understanding about the individual functions of CpeZ and CpeY in PE biogenesis in cyanobacteria, we examined PE and phycobilisomes purified from wild type F. diplosiphon, cpeZ and cpeY knockout mutants. We find that the cpeZ and cpeY mutants accumulate less PE than wild type cells. We show that in the cpeZ mutant, chromophorylation of both PE subunits is affected, especially the Cys-80 and Cys-48/Cys-59 sites of CpeB, the beta-subunit of PE. The cpeY mutant showed reduced chromophorylation at Cys-82 of CpeA. We also show that, in vitro, CpeZ stabilizes PE subunits and assists in refolding of CpeB after denaturation. Taken together, we conclude that CpeZ acts as a chaperone-like protein, assisting in the folding/stability of PE subunits, allowing bilin lyases such as CpeY and CpeS to attach PEB to their PE subunit.
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Phycoerythrin-specific bilin lyase-isomerase controls blue-green chromatic acclimation in marine Synechococcus.
Proceedings of the National Academy of Sciences of the United States of America, 2012Co-Authors: Animesh Shukla, Avijit Biswas, Frédéric Partensky, Laurence Garczarek, Wendy M. Schluchter, Jonathan A. Karty, Nicolas Blot, Loubna A Hammad, Andrian Gutu, David M. KehoeAbstract:The marine cyanobacterium Synechococcus is the second most abundant phytoplanktonic organism in the world's oceans. The ubiquity of this genus is in large part due to its use of a diverse set of photosynthetic light-harvesting pigments called phycobiliproteins, which allow it to efficiently exploit a wide range of light colors. Here we uncover a pivotal molecular mechanism underpinning a widespread response among marine Synechococcus cells known as "type IV chromatic acclimation" (CA4). During this process, the pigmentation of the two main phycobiliproteins of this organism, phycoerythrins I and II, is reversibly modified to match changes in the ambient light color so as to maximize photon capture for photosynthesis. CA4 involves the replacement of three molecules of the green light-absorbing chromophore Phycoerythrobilin with an equivalent number of the blue light-absorbing chromophore phycourobilin when cells are shifted from green to blue light, and the reverse after a shift from blue to green light. We have identified and characterized MpeZ, an enzyme critical for CA4 in marine Synechococcus. MpeZ attaches Phycoerythrobilin to cysteine-83 of the α-subunit of phycoerythrin II and isomerizes it to phycourobilin. mpeZ RNA is six times more abundant in blue light, suggesting that its proper regulation is critical for CA4. Furthermore, mpeZ mutants fail to normally acclimate in blue light. These findings provide insights into the molecular mechanisms controlling an ecologically important photosynthetic process and identify a unique class of phycoerythrin lyase/isomerases, which will further expand the already widespread use of phycoerythrin in biotechnology and cell biology applications.