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Loiseauxde S Goer - One of the best experts on this subject based on the ideXlab platform.
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the mitochondrial Pylaiella littoralis nad11 gene contains only the n terminal fes binding domain
Gene, 1999Co-Authors: M P Oudot, Bernard Kloareg, Loiseauxde S GoerAbstract:Abstract We describe a nad11 gene located on the mitochondrial genome of the brown alga Pylaiella littoralis . This gene is cotranscribed with other neighbouring nad genes. It encodes the first domain only of the Nad11 polypeptide, i.e. a 23-kDa, FeS-binding domain instead of the usual 75/80-kDa protein found in the mitochondrial or α-proteobacterial complex I enzymes. The second domain of the protein, of unknown function, seems to be entirely missing in this alga. Cyanobacteria, β-proteobacteria and actinomycetes also feature small homologous genes, known as hoxU , and it has been suggested that these could function in complex I of cyanobacteria. These observations indicate that complex I can probably function with the first domain only of the 75-kDa protein. P. littoralis represents the first such example within the α-proteobacterial/mitochondrial lineage.
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witnessing the evolution of transcription in mitochondria the mitochondrial genome of the primitive brown alga Pylaiella littoralis l kjellm encodes a t7 like rna polymerase
Journal of Molecular Biology, 1998Co-Authors: Sylvie Rousvoal, Bernard Kloareg, Jean-marc Fontaine, M P Oudot, Loiseauxde S GoerAbstract:Abstract A region of the mitochondrial genome of the primitive brown alga Pylaiella littoralis containing a plasmid-like insert which contains a transcribed T7-phage-type RNA polymerase gene is described. This is a first report of a phage-type RNA polymerase gene integrated in a mitochondrial genome. As the mitochondrial genome of this alga also contains σ-70 proteobacterial promoter regions, i.e. traces of the ancestral α 2 ββ′σ-70 proteobacterial RNA polymerase, this genome witnesses two types of RNA polymerases. As such the mitochondrial genome of P. littoralis represents a unique stage in the evolution of transcription in mitochondria, which contrasts with that of the primitive protist Reclinomonas americana , which still retains the ancestral α 2 ββ′σ-70 proteobacterial RNA polymerase genes, and with animals, land plants and fungi, which use phage-type polymerases.
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the mitochondrial lsu rdna of the brown alga Pylaiella littoralis reveals alpha proteobacterial features and is split by four group iib introns with an atypical phylogeny
Journal of Molecular Biology, 1995Co-Authors: Jean-marc Fontaine, Bernard Kloareg, Sylvie Rousvoal, Catherine Leblanc, Loiseauxde S GoerAbstract:Abstract The mitochondrial DNA region coding for the larger ribosomal RNA subunit from the brown alga Pylaiella littoralis (L.) Kjellm was sequenced. The LSU rRNA was folded into a secondary structure and aligned with homologous, mitochondrial and eubacterial sequences. Taking into account the primary and secondary structure levels, the mitochondrial LSU rRNA of P. littoralis shares more structural features with α-proteobacterial genes than do those of the green alga Prototheca wickerhamii and land plants. In phylogenetic trees, branches leading to brown algae, red algae, the protozan Acanthamoeba castellanii and land plants, respectively, emerge approximately at the same time, as they do in nuclear-gene based phylogenies. This suggests that there is only one origin for the mitochondrial rRNA genes found in these lineages. The LSU rDNA is split by four group IIB introns. The first two introns each contain one open reading frame which encodes a reverse transcriptase-like protein. Comparison of their amino acid sequences with those of other reverse transcriptase-like genes contained in group II introns shows that these genes are more closely related to plastid and cyanobacterial homologous genes than to any known mitochondrial intronic reverse transcriptase.
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characterization of the cox3 nad7 and atp6 genes from the mitochondrial genome of the brown alga Pylaiella littoralis
Plant Physiology and Biochemistry, 1995Co-Authors: Jean-marc Fontaine, Sylvie Rousvoal, N Delaroque, Loiseauxde S GoerAbstract:Mitochondrial genes from the brown alga Pylaiella littoralis (L.) Kjellm are found on the 58 kbp molecule which had been described as of plastidial origin. Three of these are described in this paper : the cox3 gene which codes for the third subunit of the cytochrome oxidase, the nad7 gene which codes for the subunit 7 of the NADH dehydrogenase (ubiquinone) complex and the atp6 gene which codes for the protein 6 of the ATP synthase A chain. The cox3 and atp6 genes are clustered as in the mitochondrial genome of the oomycete Phytophthora infestans, but their surrounding genes differ as they do for those around the nad7 gene. The cox3 and atp6 genes are cotranscribed. The atp6 gene is typically mitochondrial. The universal genetic code is used for these genes.
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secondary structure and phylogeny of the chloroplast 23s rrna gene from the brown alga Pylaiella littoralis
Plant Molecular Biology, 1993Co-Authors: C C Somerville, S Jouannic, William Martin, Bernard Kloareg, Loiseauxde S GoerAbstract:The entire nucleotide sequence of a 23S rRNA gene from the brown alga Pylaiella littoralis (L.) Kjellm has been determined. The predicted length of the 23S rRNA is 2948 nucleotides, including the 4.5S rRNA-like region at the 3' end of the molecule. The putative transcript has been folded into a secondary structure by comparison to existing structure models, and the predicted helical regions were inspected by identifying compensatory downstream base changes. The 23S rRNA secondary structure presented here has features that are unique to P. littoralis (no other chromophyte or red algal 23S rRNA sequences are yet available), but has none of the features specific to the chloroplast rRNAs of green plants and green algae. The Pylaiella sequence was aligned with analogous plastidial and eubacterial gene sequences, and the alignment was used to construct a phylogenetic tree. The plastidial sequences formed a coherent cluster closely associated with the 23S rRNA of the cyanobacterium Anacystis nidulans. Within the plastid group, the P. littoralis sequence was most closely related to that of Euglena gracilis confirming earlier analyses based upon 16S rRNA sequences.
Jean-marc Fontaine - One of the best experts on this subject based on the ideXlab platform.
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the complete sequence of a brown algal mitochondrial genome the ectocarpale Pylaiella littoralis l kjellm
Journal of Molecular Evolution, 2001Co-Authors: Marie-pierre Oudot-le Secq, Bernard Kloareg, Jean-marc Fontaine, Sylvie Rousvoal, Susan Loiseaux-de GoërAbstract:We describe here the complete sequence (58,507 bp) of the mitochondrial genome of the brown alga Pylaiella littoralis (Ectocarpales). This molecule displays an AT content of 62.0% and contains seventy-nine genes, most of them (73) encoded on one strand. They include the usual mitochondrial set of protist genes and a number of rarer genes. Among these, several ribosomal protein genes and the rn5 were identified. Twenty-four tRNA genes are present in this genome, insufficient to decode all genes. The other conspicuous features of this molecule are: a large (3018 nucleotides) in-frame insertion of unknown function in the cox2 gene; the presence of two different lineages of group II introns, including complete reverse transcriptase-like genes, one in the cox1 and the other in the rnl gene; the concomitant occurrence of a T7-like RNA polymerase and of several well-conserved α-proteobacterial-type promoters; and a small nad11 gene, coding for the first domain only of this NADH dehydrogenase subunit. Altogether, the mitochondrial genome of P. littoralis exhibits both α-proteobacterial characteristics and evidences of the independent integration of several exogenous DNA fragments.
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witnessing the evolution of transcription in mitochondria the mitochondrial genome of the primitive brown alga Pylaiella littoralis l kjellm encodes a t7 like rna polymerase
Journal of Molecular Biology, 1998Co-Authors: Sylvie Rousvoal, Bernard Kloareg, Jean-marc Fontaine, M P Oudot, Loiseauxde S GoerAbstract:Abstract A region of the mitochondrial genome of the primitive brown alga Pylaiella littoralis containing a plasmid-like insert which contains a transcribed T7-phage-type RNA polymerase gene is described. This is a first report of a phage-type RNA polymerase gene integrated in a mitochondrial genome. As the mitochondrial genome of this alga also contains σ-70 proteobacterial promoter regions, i.e. traces of the ancestral α 2 ββ′σ-70 proteobacterial RNA polymerase, this genome witnesses two types of RNA polymerases. As such the mitochondrial genome of P. littoralis represents a unique stage in the evolution of transcription in mitochondria, which contrasts with that of the primitive protist Reclinomonas americana , which still retains the ancestral α 2 ββ′σ-70 proteobacterial RNA polymerase genes, and with animals, land plants and fungi, which use phage-type polymerases.
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a group ii self splicing intron from the brown alga Pylaiella littoralis is active at unusually low magnesium concentrations and forms populations of molecules with a uniform conformation
Journal of Molecular Biology, 1997Co-Authors: Maria Do Carmo Costa, Susan Loiseaux-de Goër, Jean-marc Fontaine, Francois MichelAbstract:We have investigated the reactivity of three of the seven group II introns encoded by the mitochondrial genome of the brown alga Pylaiella littoralis. While the first intron in the protein-coding cox1 gene could not be induced to self-splice under any of the conditions tested, the first two introns in the gene encoding the large ribosomal subunit are reactive in vitro and splice primarily by the standard group II two-step transesterification pathway. Intron 2 proved to be of exceptional interest, because in contrast to all group II molecules known so far, its optimal magnesium concentration is less than 10 mM and it still carries out accurate splicing at concentrations as low as 0.1 mM magnesium. Analysis of reaction products under optimal conditions showed no evidence of hydrolysis at the 5′ splice site and up to 90% of precursor molecules could be converted into excised lariat intron, which migrated as a single band on non-denaturing polyacrylamide gels. Absorbance versus temperature profiles generated from the lariat form of intron 2 reveal the existence of an early melting component, the amplitude of which does not depend on the way the molecules were purified, i.e. with or without a denaturation step. This highly cooperative transition, whose position along the temperature axis changes with the concentration of magnesium, is proposed to consist of the unfolding of the tertiary structure of the molecule. We conclude that group II introns, which are the largest known ribozymes, can form conformationally homogeneous populations of molecules suitable for physical-chemical studies of higher-order structure.
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The Reverse-Transcriptase-Like Proteins Encoded by Group II Introns in the Mitochondrial Genome of the Brown Alga Pylaiella littoralis Belong to Two Different Lineages Which Apparently Coevolved with the Group II Ribosyme Lineages
Journal of Molecular Evolution, 1997Co-Authors: Jean-marc Fontaine, Bernard Kloareg, Didier Goux, Susan Loiseaux-de GoërAbstract:The mitochondrial genome of the brown alga Pylaiella littoralis contains two different types of group II introns. They each encode complete complex proteins, i.e., with a reverse transcriptase domain, a maturase or X domain, and an endonuclease or H-N-H/zinc finger domain. To our knowledge, this is the first example of the presence in the same genome of introns belonging to subgroups IIA and IIB which both contain multidomained RT-like proteins. We describe the group IIA introns that interrupt the cox1 gene. The RT-like proteins contained in these introns were compared to those of the LSU rDNA group IIB introns. The phylogenetic relationships of these intron ORFs were investigated and the possible evolution of group II introns is discussed.
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structure et evolution du genome mitochondrial de l algue brune Pylaiella littoralis
1996Co-Authors: Jean-marc FontaineAbstract:Le genome mitochondrial de Pylaiella littoralis est un genome circulaire de taille moyenne, 58 kbp. Le sequencage systematique de chaque clone representatif de ce genome a permis d'etablir une carte genomique presque complete, d'identifier une cinquantaine de genes, et de localiser la presence de zones promotrices putatives de type eubacterien a facteur -70. La phylogenie du gene 23s a ete etudie, ceci par la realisation de la structure secondaire et de l'alignement de sa sequence avec celles de genes homologues provenant d'autres organismes. Les resultats montrent que ce gene est plus proche de ceux des proteobacteries que ceux des autres organismes. Un total de quatre introns de groupe iib a ete identifie dans le gene specifiant l'arn 23s et de trois introns de groupe iia dans le gene specifiant le coxi. Ces introns sont des arns autocatalytiques, c'est a dire ayant la possibilite de s'autoepisser in vitro. Certains de ces introns peuvent posseder des phases de lecture ouverte (orfs) apparentees a des transcriptases inverses (ti). Des etudes phylogenetiques fondees d'une part sur les orfs des introns de groupe iib et d'autre part sur les orfs des introns de groupe iia montrent que les deux premiers introns du 23s semblent avoir un ancetre commun avec un intron present dans les cyanobacteries et les plastes, et de facon surprenante, sont moins proches de ceux des mitochondries de levures et de marchantia polymorpha. Au contraire les ti contenues dans les trois introns du gene coxi sont proches des ti de tous les introns mitochondriaux connus. Nous avons montres que ces orf coevoluent avec les introns et appartiennent a deux lignees differentes. Nous discutons egalement de l'origine de ces introns. Des experiences d'autoepissage in vitro pour certains de ces introns ont permis d'observer une forte activite d'autoepissage a tres basse concentration en mgcl#2, ce qui constitue le premier exemple d'autoepissage se rapprochant des conditions physiologiques. En resume il semble que cette molecule ait conserve des caracteristiques plus primitives que les autres genomes mitochondriaux etudies. Ces resultats sont discutes dans le cadre de la theorie endosymbiotique sur l'origine et l'evolution des mitochondries
Susan Loiseaux-de Goër - One of the best experts on this subject based on the ideXlab platform.
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Complete mitochondrial genomes of the three brown algae (Heterokonta: Phaeophyceae) Dictyota dichotoma, Fucus vesiculosus and Desmarestia viridis
Current Genetics, 2006Co-Authors: Marie-pierre Oudot-le Secq, Susan Loiseaux-de Goër, Wytze T. Stam, Jeanine L. OlsenAbstract:We report the complete mitochondrial sequences of three brown algae ( Dictyota dichotoma , Fucus vesiculosus and Desmarestia viridis ) belonging to three phaeophycean lineages. They have circular mapping organization and contain almost the same set of mitochondrial genes, despite their size differences (31,617, 36,392 and 39,049 bp, respectively). These include the genes for three rRNAs (23S, 16S and 5S), 25–26 tRNAs, 35 known mitochondrial proteins and 3–4 ORFs. This gene set complements two previously studied brown algal mtDNAs, Pylaiella littoralis and Laminaria digitata . Exceptions to the very similar overall organization include the displacement of orf s, tRNA genes and four protein-coding genes found at different locations in the D. dichotoma mitochondrial genome. We present a phylogenetic analysis based on ten concatenated genes (7,479 nucleotides) and 29 taxa. Stramenopiles were always monophyletic with heterotrophic species at the base. Results support both multiple primary and multiple secondary acquisitions of plastids.
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the complete sequence of a brown algal mitochondrial genome the ectocarpale Pylaiella littoralis l kjellm
Journal of Molecular Evolution, 2001Co-Authors: Marie-pierre Oudot-le Secq, Bernard Kloareg, Jean-marc Fontaine, Sylvie Rousvoal, Susan Loiseaux-de GoërAbstract:We describe here the complete sequence (58,507 bp) of the mitochondrial genome of the brown alga Pylaiella littoralis (Ectocarpales). This molecule displays an AT content of 62.0% and contains seventy-nine genes, most of them (73) encoded on one strand. They include the usual mitochondrial set of protist genes and a number of rarer genes. Among these, several ribosomal protein genes and the rn5 were identified. Twenty-four tRNA genes are present in this genome, insufficient to decode all genes. The other conspicuous features of this molecule are: a large (3018 nucleotides) in-frame insertion of unknown function in the cox2 gene; the presence of two different lineages of group II introns, including complete reverse transcriptase-like genes, one in the cox1 and the other in the rnl gene; the concomitant occurrence of a T7-like RNA polymerase and of several well-conserved α-proteobacterial-type promoters; and a small nad11 gene, coding for the first domain only of this NADH dehydrogenase subunit. Altogether, the mitochondrial genome of P. littoralis exhibits both α-proteobacterial characteristics and evidences of the independent integration of several exogenous DNA fragments.
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a group ii self splicing intron from the brown alga Pylaiella littoralis is active at unusually low magnesium concentrations and forms populations of molecules with a uniform conformation
Journal of Molecular Biology, 1997Co-Authors: Maria Do Carmo Costa, Susan Loiseaux-de Goër, Jean-marc Fontaine, Francois MichelAbstract:We have investigated the reactivity of three of the seven group II introns encoded by the mitochondrial genome of the brown alga Pylaiella littoralis. While the first intron in the protein-coding cox1 gene could not be induced to self-splice under any of the conditions tested, the first two introns in the gene encoding the large ribosomal subunit are reactive in vitro and splice primarily by the standard group II two-step transesterification pathway. Intron 2 proved to be of exceptional interest, because in contrast to all group II molecules known so far, its optimal magnesium concentration is less than 10 mM and it still carries out accurate splicing at concentrations as low as 0.1 mM magnesium. Analysis of reaction products under optimal conditions showed no evidence of hydrolysis at the 5′ splice site and up to 90% of precursor molecules could be converted into excised lariat intron, which migrated as a single band on non-denaturing polyacrylamide gels. Absorbance versus temperature profiles generated from the lariat form of intron 2 reveal the existence of an early melting component, the amplitude of which does not depend on the way the molecules were purified, i.e. with or without a denaturation step. This highly cooperative transition, whose position along the temperature axis changes with the concentration of magnesium, is proposed to consist of the unfolding of the tertiary structure of the molecule. We conclude that group II introns, which are the largest known ribozymes, can form conformationally homogeneous populations of molecules suitable for physical-chemical studies of higher-order structure.
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molecular phylogeny of the atpb and atpe genes of the brown alga Pylaiella littoralis
European Journal of Phycology, 1993Co-Authors: William Martin, S Jouannic, Susan Loiseaux-de GoërAbstract:Recent phylogenetic studies suggest that plastid ribosomal RNA genes from Pylaiella littoralis have a cyanobacterial origin, whereas their Rubisco genes are related to the homologous α- and β- purple eubacterial genes. We have constructed a phylogenetic tree based upon the atpB and atpE sequences, including the same range of taxa (chlorophytes, chromophytes, cyanobacteria, α- and γ-purple eubacteria) and using the same methods as previously described for rbcL genes. This phylogenetic tree clearly shows that the atpB and atpE genes of this brown alga are more closely related to their cyanobacterial homologues than to those of α- or γ-purple eubacteria. Different hypotheses that could explain the apparently composite origin of red-chromophyte plastomes are discussed.
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sequence and phylogeny of the psab gene of Pylaiella littoralis phaeophyta 1
Journal of Phycology, 1992Co-Authors: Noureddine Assali, Susan Loiseaux-de GoërAbstract:The psaB gene codes for one of two highly conserved P 700 chlorophyll a apoproteins of photosystem I. This gene was cloned from the brown alga, Pylaiella littoralis (L.) Kjellm., and its primary sequence was determined. The inferred amino acid sequence of the P. littoralis protein was compared to homologous sequences from land plants, green algae, and a cyanobacterium. The psaB protein sequence is very conserved in all the examined taxa, and an unrooted phylogenetic tree, generated from a distance matrix, shows that the P. littoralis gene is closer to that of the cyanobacterium Synechococcus sp. PCC 7002 than are those of green algae, land plants, and Euglena gracilis
Bernard Kloareg - One of the best experts on this subject based on the ideXlab platform.
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the complete sequence of a brown algal mitochondrial genome the ectocarpale Pylaiella littoralis l kjellm
Journal of Molecular Evolution, 2001Co-Authors: Marie-pierre Oudot-le Secq, Bernard Kloareg, Jean-marc Fontaine, Sylvie Rousvoal, Susan Loiseaux-de GoërAbstract:We describe here the complete sequence (58,507 bp) of the mitochondrial genome of the brown alga Pylaiella littoralis (Ectocarpales). This molecule displays an AT content of 62.0% and contains seventy-nine genes, most of them (73) encoded on one strand. They include the usual mitochondrial set of protist genes and a number of rarer genes. Among these, several ribosomal protein genes and the rn5 were identified. Twenty-four tRNA genes are present in this genome, insufficient to decode all genes. The other conspicuous features of this molecule are: a large (3018 nucleotides) in-frame insertion of unknown function in the cox2 gene; the presence of two different lineages of group II introns, including complete reverse transcriptase-like genes, one in the cox1 and the other in the rnl gene; the concomitant occurrence of a T7-like RNA polymerase and of several well-conserved α-proteobacterial-type promoters; and a small nad11 gene, coding for the first domain only of this NADH dehydrogenase subunit. Altogether, the mitochondrial genome of P. littoralis exhibits both α-proteobacterial characteristics and evidences of the independent integration of several exogenous DNA fragments.
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the mitochondrial Pylaiella littoralis nad11 gene contains only the n terminal fes binding domain
Gene, 1999Co-Authors: M P Oudot, Bernard Kloareg, Loiseauxde S GoerAbstract:Abstract We describe a nad11 gene located on the mitochondrial genome of the brown alga Pylaiella littoralis . This gene is cotranscribed with other neighbouring nad genes. It encodes the first domain only of the Nad11 polypeptide, i.e. a 23-kDa, FeS-binding domain instead of the usual 75/80-kDa protein found in the mitochondrial or α-proteobacterial complex I enzymes. The second domain of the protein, of unknown function, seems to be entirely missing in this alga. Cyanobacteria, β-proteobacteria and actinomycetes also feature small homologous genes, known as hoxU , and it has been suggested that these could function in complex I of cyanobacteria. These observations indicate that complex I can probably function with the first domain only of the 75-kDa protein. P. littoralis represents the first such example within the α-proteobacterial/mitochondrial lineage.
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witnessing the evolution of transcription in mitochondria the mitochondrial genome of the primitive brown alga Pylaiella littoralis l kjellm encodes a t7 like rna polymerase
Journal of Molecular Biology, 1998Co-Authors: Sylvie Rousvoal, Bernard Kloareg, Jean-marc Fontaine, M P Oudot, Loiseauxde S GoerAbstract:Abstract A region of the mitochondrial genome of the primitive brown alga Pylaiella littoralis containing a plasmid-like insert which contains a transcribed T7-phage-type RNA polymerase gene is described. This is a first report of a phage-type RNA polymerase gene integrated in a mitochondrial genome. As the mitochondrial genome of this alga also contains σ-70 proteobacterial promoter regions, i.e. traces of the ancestral α 2 ββ′σ-70 proteobacterial RNA polymerase, this genome witnesses two types of RNA polymerases. As such the mitochondrial genome of P. littoralis represents a unique stage in the evolution of transcription in mitochondria, which contrasts with that of the primitive protist Reclinomonas americana , which still retains the ancestral α 2 ββ′σ-70 proteobacterial RNA polymerase genes, and with animals, land plants and fungi, which use phage-type polymerases.
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The Reverse-Transcriptase-Like Proteins Encoded by Group II Introns in the Mitochondrial Genome of the Brown Alga Pylaiella littoralis Belong to Two Different Lineages Which Apparently Coevolved with the Group II Ribosyme Lineages
Journal of Molecular Evolution, 1997Co-Authors: Jean-marc Fontaine, Bernard Kloareg, Didier Goux, Susan Loiseaux-de GoërAbstract:The mitochondrial genome of the brown alga Pylaiella littoralis contains two different types of group II introns. They each encode complete complex proteins, i.e., with a reverse transcriptase domain, a maturase or X domain, and an endonuclease or H-N-H/zinc finger domain. To our knowledge, this is the first example of the presence in the same genome of introns belonging to subgroups IIA and IIB which both contain multidomained RT-like proteins. We describe the group IIA introns that interrupt the cox1 gene. The RT-like proteins contained in these introns were compared to those of the LSU rDNA group IIB introns. The phylogenetic relationships of these intron ORFs were investigated and the possible evolution of group II introns is discussed.
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the mitochondrial lsu rdna of the brown alga Pylaiella littoralis reveals alpha proteobacterial features and is split by four group iib introns with an atypical phylogeny
Journal of Molecular Biology, 1995Co-Authors: Jean-marc Fontaine, Bernard Kloareg, Sylvie Rousvoal, Catherine Leblanc, Loiseauxde S GoerAbstract:Abstract The mitochondrial DNA region coding for the larger ribosomal RNA subunit from the brown alga Pylaiella littoralis (L.) Kjellm was sequenced. The LSU rRNA was folded into a secondary structure and aligned with homologous, mitochondrial and eubacterial sequences. Taking into account the primary and secondary structure levels, the mitochondrial LSU rRNA of P. littoralis shares more structural features with α-proteobacterial genes than do those of the green alga Prototheca wickerhamii and land plants. In phylogenetic trees, branches leading to brown algae, red algae, the protozan Acanthamoeba castellanii and land plants, respectively, emerge approximately at the same time, as they do in nuclear-gene based phylogenies. This suggests that there is only one origin for the mitochondrial rRNA genes found in these lineages. The LSU rDNA is split by four group IIB introns. The first two introns each contain one open reading frame which encodes a reverse transcriptase-like protein. Comparison of their amino acid sequences with those of other reverse transcriptase-like genes contained in group II introns shows that these genes are more closely related to plastid and cyanobacterial homologous genes than to any known mitochondrial intronic reverse transcriptase.
J. Perea - One of the best experts on this subject based on the ideXlab platform.
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The brown algae Pl.LSU/2 group II intron-encoded protein has functional reverse transcriptase and maturase activities
PLoS ONE, 2013Co-Authors: M. Zerbato, N. Holic, S. Moniot-frin, D. Ingrao, A. Galy, J. PereaAbstract:Group II introns are self-splicing mobile elements found in prokaryotes and eukaryotic organelles. These introns propagate by homing into precise genomic locations, following assembly of a ribonucleoprotein complex containing the intron-encoded protein (IEP) and the spliced intron RNA. Engineered group II introns are now commonly used tools for targeted genomic modifications in prokaryotes but not in eukaryotes. We speculate that the catalytic activation of currently known group II introns is limited in eukaryotic cells. The brown algae Pylaiella littoralis Pl.LSU/2 group II intron is uniquely capable of in vitro ribozyme activity at physiological level of magnesium but this intron remains poorly characterized. We purified and characterized recombinant Pl.LSU/2 IEP. Unlike most IEPs, Pl.LSU/2 IEP displayed a reverse transcriptase activity without intronic RNA. The Pl.LSU/2 intron could be engineered to splice accurately in Saccharomyces cerevisiae and splicing efficiency was increased by the maturase activity of the IEP. However, spliced transcripts were not expressed. Furthermore, intron splicing was not detected in human cells. While further tool development is needed, these data provide the first functional characterization of the PI.LSU/2 IEP and the first evidence that the Pl.LSU/2 group II intron splicing occurs in vivo in eukaryotes in an IEP-dependent manner.
