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Nancy M. Dahms - One of the best experts on this subject based on the ideXlab platform.
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identification of a fourth Mannose 6 Phosphate binding site in the cation independent Mannose 6 Phosphate receptor
Glycobiology, 2015Co-Authors: Linda J. Olson, Richard D Cummings, David F Smith, Alicia C Castonguay, Yi Lasanajak, Francis C Peterson, Nancy M. DahmsAbstract:The 300 kDa cation-independent Mannose 6-Phosphate receptor (CI-MPR) plays an essential role in lysosome biogenesis by targeting ∼ 60 different phosphomannosyl-containing acid hydrolases to the lysosome. This type I membrane glycoprotein has a large extracellular region comprised of 15 homologous domains. Two Mannose 6-Phosphate (M6P) binding sites have been mapped to domains 3 and 9, whereas domain 5 binds preferentially to the phosphodiester, M6P-N-acetylglucosamine (GlcNAc). A structure-based sequence alignment predicts that the C-terminal domain 15 contains three out of the four conserved residues identified as essential for carbohydrate recognition by domains 3, 5 and 9 of the CI-MPR, but lacks two cysteine residues that are predicted to form a disulfide bond. To determine whether domain 15 of the CI-MPR has lectin activity and to probe its carbohydrate-binding specificity, truncated forms of the CI-MPR were tested for binding to acid hydrolases with defined N-glycans in surface plasmon resonance analyses, and used to interrogate a phosphorylated glycan microarray. The results show that a construct encoding domains 14-15 binds both M6P and M6P-GlcNAc with similar affinity (Kd = 13 and 17 μM, respectively). Site-directed mutagenesis studies demonstrate the essential role of the conserved Tyr residue in domain 15 for phosphomannosyl binding. A structural model of domain 15 was generated that predicted an Arg residue to be in the binding pocket and mutagenesis studies confirmed its important role in carbohydrate binding. Together, these results show that the CI-MPR contains a fourth carbohydrate-recognition site capable of binding both phosphomonoesters and phosphodiesters.
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cation independent Mannose 6 Phosphate receptor a composite of distinct phosphomannosyl binding sites
Journal of Biological Chemistry, 2009Co-Authors: Richard N Bohnsack, Linda J. Olson, William M. Canfield, Xuezheng Song, Mariko Kudo, Russell Gotschall, Richard D Cummings, David F Smith, Nancy M. DahmsAbstract:Abstract The 300-kDa cation-independent Mannose 6-Phosphate receptor (CI-MPR), which contains multiple Mannose 6-Phosphate (Man-6-P) binding sites that map to domains 3, 5, and 9 within its 15-domain extracytoplasmic region, functions as an efficient carrier of Man-6-P-containing lysosomal enzymes. To determine the types of phosphorylated N-glycans recognized by each of the three carbohydrate binding sites of the CI-MPR, a phosphorylated glycan microarray was probed with truncated forms of the CI-MPR. Surface plasmon resonance analyses using lysosomal enzymes with defined N-glycans were performed to evaluate whether multiple domains are needed to form a stable, high affinity carbohydrate binding pocket. Like domain 3, adjacent domains increase the affinity of domain 5 for phosphomannosyl residues, with domain 5 exhibiting ∼60-fold higher affinity for lysosomal enzymes containing the phosphodiester Man-P-GlcNAc when in the context of a construct encoding domains 5–9. In contrast, domain 9 does not require additional domains for high affinity binding. The three sites differ in their glycan specificity, with only domain 5 being capable of recognizing Man-P-GlcNAc. In addition, domain 9, unlike domains 1–3, interacts with Man8GlcNAc2 and Man9GlcNAc2 oligosaccharides containing a single phosphomonoester. Together, these data indicate that the assembly of three unique carbohydrate binding sites allows the CI-MPR to interact with the structurally diverse phosphorylated N-glycans it encounters on newly synthesized lysosomal enzymes.
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Carbohydrate recognition by the Mannose-6-Phosphate receptors.
Current opinion in structural biology, 2009Co-Authors: Jung-ja P. Kim, Linda J. Olson, Nancy M. DahmsAbstract:The two P-type lectins, the 46 kDa cation-dependent Mannose-6-Phosphate (Man-6-P) receptor (CD-MPR), and the 300 kDa cation-independent Man-6-P receptor (CI-MPR), are the founding members of the growing family of Mannose-6-Phosphate receptor homology (MRH) proteins. A major cellular function of the MPRs is to transport Man-6-P-containing acid hydrolases from the Golgi to endosomal/lysosomal compartments. Recent advances in the structural analyses of both CD-MPR and CI-MPR have revealed the structural basis for phosphomannosyl recognition by these receptors and provided insights into how the receptors load and unload their cargo. A surprising finding is that the CD-MPR is dynamic, with at least two stable quaternary states, the open (ligand-bound) and closed (ligand-free) conformations, similar to those of hemoglobin. Ligand binding stabilizes the open conformation; changes in the pH of the environment at the cell surface and in endosomal compartments weaken the ligand–receptor interaction and/or weaken the electrostatic interactions at the subunit interface, resulting in the closed conformation.
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strategies for carbohydrate recognition by the Mannose 6 Phosphate receptors
Glycobiology, 2008Co-Authors: Nancy M. Dahms, Linda J. Olson, Jung-ja P. KimAbstract:The two members of the P-type lectin family, the 46 kDa cation-dependent Mannose 6-Phosphate receptor (CD-MPR) and the 300 kDa cation-independent Mannose 6-Phosphate receptor (CI-MPR), are ubiquitously expressed throughout the animal kingdom and are distinguished from all other lectins by their ability to recognize phosphorylated Mannose residues. The best-characterized function of the MPRs is their ability to direct the delivery of ~60 different newly synthesized soluble lysosomal enzymes bearing Mannose 6-Phosphate (Man-6-P) on their N-linked oligosaccharides to the lysosome. In addition to its intracellular role in lysosome biogenesis, the CI-MPR, but not the CD-MPR, participates in a number of other biological processes by interacting with various molecules at the cell surface. The list of extracellular ligands recognized by this multifunctional receptor has grown to include a diverse spectrum of Man-6-P-containing proteins as well as several non-Man-6-P-containing ligands. Recent structural studies have given us a clearer view of how these two receptors use related, but yet distinct, approaches in the recognition of phosphomannosyl residues.
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strategies for carbohydrate recognition by the Mannose 6 Phosphate receptors
Glycobiology, 2008Co-Authors: Nancy M. Dahms, Linda J. Olson, Jung-ja P. KimAbstract:The two members of the P-type lectin family, the 46 kDa cation-dependent Mannose 6-Phosphate receptor (CD-MPR) and the 300 kDa cation-independent Mannose 6-Phosphate receptor (CI-MPR), are ubiquitously expressed throughout the animal kingdom and are distinguished from all other lectins by their ability to recognize phosphorylated Mannose residues. The best-characterized function of the MPRs is their ability to direct the delivery of approximately 60 different newly synthesized soluble lysosomal enzymes bearing Mannose 6-Phosphate (Man-6-P) on their N-linked oligosaccharides to the lysosome. In addition to its intracellular role in lysosome biogenesis, the CI-MPR, but not the CD-MPR, participates in a number of other biological processes by interacting with various molecules at the cell surface. The list of extracellular ligands recognized by this multifunctional receptor has grown to include a diverse spectrum of Man-6-P-containing proteins as well as several non-Man-6-P-containing ligands. Recent structural studies have given us a clearer view of how these two receptors use related, but yet distinct, approaches in the recognition of phosphomannosyl residues.
Stuart Kornfeld - One of the best experts on this subject based on the ideXlab platform.
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Mannose 6-Phosphate-independent Targeting of Lysosomal Enzymes in I-CeU Disease
2013Co-Authors: B Lymphoblasts, Jonathan N. Glickman, Stuart KornfeldAbstract:Abstract. B lymphocytes from patients with I-cell disease (ICD) maintain normal cellular levels of lysosomal enzymes despite a deficiency of the enzyme UDP-N-acetylglucosamine: lysosomal enzyme N-acetylglucosamine-l-phosphotransferase. We find that an ICD B lymphoblastoid cell line targets about 45 % of the lysosomal protease cathepsin D to dense lysosomes. This targeting occurs in the absence of detectable Mannose 6-Phosphate residues on the cathepsin D and is not observed in ICD fibroblasts. The secretory protein pepsinogen, which is closely related to cathepsin D in both amino acid sequence and threedimensional structure, is mostly excluded from dense lysosomes, indicating that the lymphoblast targeting pathway is specific. Carbohydrate residues are no
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analysis of Mannose 6 Phosphate uncovering enzyme mutations associated with persistent stuttering
Journal of Biological Chemistry, 2011Co-Authors: Wang Sik Lee, Changsoo Kang, Dennis Drayna, Stuart KornfeldAbstract:GlcNAc-1-phosphodiester-N-acetylglucosaminidase ("uncovering enzyme" (UCE); EC 3.1.4.45) is a Golgi enzyme that mediates the second step in the synthesis of the Mannose 6-Phosphate lysosomal targeting signal on acid hydrolases. Recently, three mutations (two missense and one deletion/frameshift) in the NAGPA gene that encodes UCE have been identified in individuals with persistent stuttering. We now demonstrate that each mutation leads to lower cellular UCE activity. The p.R328C mutation impairs folding in the endoplasmic reticulum, resulting in degradation of a significant portion by the proteasomal system. The p.H84Q mutation also impairs folding and, in addition, decreases the specific activity of the enzyme that folds sufficiently to traffic to the Golgi. The p.F513SfsX113 frameshift mutation adds 113 amino acids to the C terminus of the cytoplasmic tail of the protein, including a VWLL sequence that causes rapid degradation via the proteasomal system. These biochemical findings extend the genetic data implicating mutations in the NAGPA gene in the persistent stuttering phenotype.
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mammalian ggas act together to sort Mannose 6 Phosphate receptors
Journal of Cell Biology, 2003Co-Authors: Pradipta Ghosh, Janice Griffith, Hans J Geuze, Stuart KornfeldAbstract:The GGAs (Golgi-localized, γ ear–containing, ADP ribosylation factor–binding proteins) are multidomain proteins implicated in protein trafficking between the Golgi and endosomes. We examined whether the three mammalian GGAs act independently or together to mediate their functions. Using cryo-immunogold electron microscopy, the three GGAs were shown to colocalize within coated buds and vesicles at the trans-Golgi network (TGN) of HeLa cells. In vitro binding experiments revealed multidomain interactions between the GGAs, and chemical cross-linking experiments demonstrated that GGAs 1 and 2 form a complex on Golgi membranes. RNA interference of each GGA resulted in decreased levels of the other GGAs and their redistribution from the TGN to cytosol. This was associated with impaired incorporation of the cation-independent Mannose 6-Phosphate receptor into clathrin-coated vesicles at the TGN, partial redistribution of the receptor to endosomes, and missorting of cathepsin D. The morphology of the TGN was also altered. These findings indicate that the three mammalian GGAs cooperate to sort cargo and are required for maintenance of TGN structure.
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Mannose 6 Phosphate receptors new twists in the tale
Nature Reviews Molecular Cell Biology, 2003Co-Authors: Pradipta Ghosh, Nancy M. Dahms, Stuart KornfeldAbstract:The two Mannose 6-Phosphate (M6P) receptors were identified because of their ability to bind M6P-containing soluble acid hydrolases in the Golgi and transport them to the endosomal-lysosomal system. During the past decade, we have started to understand the structural features of these receptors that allow them to do this job, and how the receptors themselves are sorted as they pass through various membrane-bound compartments. But trafficking of acid hydrolases is only part of the story. Evidence is emerging that one of the receptors can regulate cell growth and motility, and that it functions as a tumour suppressor.
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binding of gga2 to the lysosomal enzyme sorting motif of the Mannose 6 Phosphate receptor
Science, 2001Co-Authors: Balraj Doray, Anssi Poussu, Velipekka Lehto, Stuart KornfeldAbstract:The GGAs are a multidomain protein family implicated in protein trafficking between the Golgi and endosomes. Here, the VHS domain of GGA2 was shown to bind to the acidic cluster–dileucine motif in the cytoplasmic tail of the cation-independent Mannose 6-Phosphate receptor (CI-MPR). Receptors with mutations in this motif were defective in lysosomal enzyme sorting. The hinge domain of GGA2 bound clathrin, suggesting that GGA2 could be a link between cargo molecules and clathrin-coated vesicle assembly. Thus, GGA2 binding to the CI-MPR is important for lysosomal enzyme targeting.
William A Banks - One of the best experts on this subject based on the ideXlab platform.
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Human Immunodeficiency Virus-1 Uses the Mannose-6- Phosphate Receptor to Cross the Blood-Brain Barrier
2016Co-Authors: Shinya Dohgu, Jan S Ryerse, Ra M. Robinson, William A BanksAbstract:HIV-1 circulates both as free virus and within immune cells, with the level of free virus being predictive of clinical course. Both forms of HIV-1 cross the blood-brain barrier (BBB) and much progress has been made in understanding the mechanisms by which infected immune cells cross the blood-brain barrier BBB. How HIV-1 as free virus crosses the BBB is less clear as brain endothelial cells are CD4 and galactosylceramide negative. Here, we found that HIV-1 can use the Mannose-6 Phosphate receptor (M6PR) to cross the BBB. Brain perfusion studies showed that HIV-1 crossed the BBB of all brain regions consistent with the uniform distribution of M6PR. Ultrastructural studies showed HIV-1 crossed by a transcytotic pathway consistent with transport by M6PR. An in vitro model of the BBB was used to show that transport of HIV-1 was inhibited by Mannose, mannan, and Mannose-6 Phosphate and that enzymatic removal of high Mannose oligosaccharide residues from HIV-1 reduced transport. Wheatgerm agglutinin and protamine sulfate, substances known to greatly increase transcytosis of HIV-1 across the BBB in vivo, were shown to be active in the in vitro model and to act through a Mannose-dependent mechanism. Transport was also cAMP and calcium-dependent, the latter suggesting tha
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human immunodeficiency virus 1 uses the Mannose 6 Phosphate receptor to cross the blood brain barrier
PLOS ONE, 2012Co-Authors: Shinya Dohgu, Jan S Ryerse, Sandra M Robinson, William A BanksAbstract:HIV-1 circulates both as free virus and within immune cells, with the level of free virus being predictive of clinical course. Both forms of HIV-1 cross the blood-brain barrier (BBB) and much progress has been made in understanding the mechanisms by which infected immune cells cross the blood-brain barrier BBB. How HIV-1 as free virus crosses the BBB is less clear as brain endothelial cells are CD4 and galactosylceramide negative. Here, we found that HIV-1 can use the Mannose-6 Phosphate receptor (M6PR) to cross the BBB. Brain perfusion studies showed that HIV-1 crossed the BBB of all brain regions consistent with the uniform distribution of M6PR. Ultrastructural studies showed HIV-1 crossed by a transcytotic pathway consistent with transport by M6PR. An in vitro model of the BBB was used to show that transport of HIV-1 was inhibited by Mannose, mannan, and Mannose-6 Phosphate and that enzymatic removal of high Mannose oligosaccharide residues from HIV-1 reduced transport. Wheatgerm agglutinin and protamine sulfate, substances known to greatly increase transcytosis of HIV-1 across the BBB in vivo, were shown to be active in the in vitro model and to act through a Mannose-dependent mechanism. Transport was also cAMP and calcium-dependent, the latter suggesting that the cation-dependent member of the M6PR family mediates HIV-1 transport across the BBB. We conclude that M6PR is an important receptor used by HIV-1 to cross the BBB.
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developmentally regulated Mannose 6 Phosphate receptor mediated transport of a lysosomal enzyme across the blood brain barrier
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Akihiko Urayama, Jeffrey H. Grubb, William S. Sly, William A BanksAbstract:Mucopolysaccharidosis type VII is a lysosomal storage disorder resulting from inherited deficiency of β-glucuronidase (GUS). Mucopolysaccharidosis type VII is characterized by glycosaminoglycan storage in most tissues, including brain. In these disorders, enzyme delivery across the blood-brain barrier (BBB) is the main obstacle to correction of lysosomal storage in the CNS. Prior studies suggested mouse brain is accessible to GUS in the first 2 weeks of life but not later. To explore a possible role for the Mannose 6-Phosphate/insulin-like growth factor II receptor in GUS transport across the BBB in neonatal mice, we compared brain uptake of phosphorylated GUS (P-GUS) and nonphosphorylated GUS (NP-GUS) in newborn and adult mice. 131I-P-GUS was transported across the BBB after i.v. injection in 2-day-old mice. The brain influx rate (Kin) of 131I-P-GUS in 2-day-old mice was 0.21 μl/g·min and decreased with age. By 7 weeks of age, transport of 131I-P-GUS was not significant. Capillary depletion revealed that 62% of the 131I-P-GUS in brain was in brain parenchyma in 2-day-old mice. In addition, uptake of 131I-P-GUS into brain was significantly reduced by coinjection of unlabeled P-GUS or M6P in a dose-dependent manner. In contrast, the Kin of 131I-NP-GUS (0.04 μl/g·min) was significantly lower than 131I-P-GUS in 2-day-old mice. Transcardiac brain perfusion confirmed that neither 131I-P-GUS nor 131I-NP-GUS crossed the BBB in adult mice. These results indicate that 131I-P-GUS transport into brain parenchyma in early postnatal life is mediated by the Mannose 6-Phosphate/insulin-like growth factor II receptor. This receptor-mediated transport is not observed in adult mice.
Soo Jin Yeom - One of the best experts on this subject based on the ideXlab platform.
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production of l ribose from l ribulose by a triple site variant of Mannose 6 Phosphate isomerase from geobacillus thermodenitrificans
Applied and Environmental Microbiology, 2012Co-Authors: Yuri Lim, Soo Jin YeomAbstract:A triple-site variant (W17Q N90A L129F) of Mannose-6-Phosphate isomerase from Geobacillus thermodenitrificans was obtained by combining variants with residue substitutions at different positions after random and site-directed mutagenesis. The specific activity and catalytic efficiency (kcat/Km) for l-ribulose isomerization of this variant were 3.1- and 7.1-fold higher, respectively, than those of the wild-type enzyme at pH 7.0 and 70°C in the presence of 1 mM Co2+. The triple-site variant produced 213 g/liter l-ribose from 300 g/liter l-ribulose for 60 min, with a volumetric productivity of 213 g liter−1 h−1, which was 4.5-fold higher than that of the wild-type enzyme. The kcat/Km and productivity of the triple-site variant were approximately 2-fold higher than those of the Thermus thermophilus R142N variant of Mannose-6-Phosphate isomerase, which exhibited the highest values previously reported.
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molecular characterization of a novel thermostable Mannose 6 Phosphate isomerase from thermus thermophilus
Biochimie, 2011Co-Authors: Soo Jin Yeom, Yuri Lim, Yeongsu Kim, Kiwoong Jeong, Jeeyoung Lee, Yangmee KimAbstract:Abstract Mannose-6-Phosphate isomerase catalyzes the interconversion of Mannose-6-Phosphate and fructose-6-Phosphate. The gene encoding a putative Mannose-6-Phosphate isomerase from Thermus thermophilus was cloned and expressed in Escherichia coli. The native enzyme was a 29 kDa monomer with activity maxima for Mannose 6-Phosphate at pH 7.0 and 80 °C in the presence of 0.5 mM Zn2+ that was present at one molecule per monomer. The half-lives of the enzyme at 65, 70, 75, 80, and 85 °C were 13, 6.5, 3.7, 1.8, and 0.2 h, respectively. The 15 putative active-site residues within 4.5 A of the substrate Mannose 6-Phosphate in the homology model were individually replaced with other amino acids. The sequence alignments, activities, and kinetic analyses of the wild-type and mutant enzymes with amino acid changes at His50, Glu67, His122, and Glu132 as well as homology modeling suggested that these four residues are metal-binding residues and may be indirectly involved in catalysis. In the model, Arg11, Lys37, Gln48, Lys65 and Arg142 were located within 3 A of the bound Mannose 6-Phosphate. Alanine substitutions of Gln48 as well as Arg142 resulted in increase of Km and dramatic decrease of kcat, and alanine substitutions of Arg11, Lys37, and Lys65 affected enzyme activity. These results suggest that these 5 residues are substrate-binding residues. Although Trp13 was located more than 3 A from the substrate and may not interact directly with substrate or metal, the ring of Trp13 was essential for enzyme activity.
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characterization of a Mannose 6 Phosphate isomerase from thermus thermophilus and increased l ribose production by its r142n mutant
Applied and Environmental Microbiology, 2011Co-Authors: Soo Jin Yeom, Deok-kun OhAbstract:Optically pure carbohydrates are important precursors for pharmaceutical, food, and agrochemical products (22). Among carbohydrates, l-enantiomers have been widely used as antiviral nucleoside analogue drugs in the treatment of severe viral diseases due to their potent biological activities and lower toxicity than the corresponding d-nucleosides (3). l-Ribose, a pentose sugar, can be used as a precursor for the synthesis of antiviral drugs, such as l-nucleoside derivatives (2, 5, 14). l-Ribose can be synthesized by chemical methods from l-arabinose (1, 6, 9), l-xylose (13), d-glucose (15), d-galactose (19), d-ribose (26), or d-mannono-1,4-lactone (20). However, chemical synthesis has several disadvantages, including multiple steps, by-product formation, and chemical waste production. Recently, the enzymatic production of l-ribose has been investigated using l-arabinose (7) or l-ribulose (25). l-Ribose has been produced primarily from the cheap sugar l-arabinose because l-ribulose is an expensive sugar. An l-arabinose isomerase mutant of Escherichia coli (4) and a d-xylose isomerase mutant of Actinoplanes missouriensis (17) converted l-arabinose to l-ribose by a two-step isomerization reaction with low productivity. A recombinant E. coli strain containing l-arabinose isomerase and l-ribose isomerase (7) and purified l-arabinose isomerase and Mannose-6-Phosphate isomerase from Geobacillus thermodenitrificans (24) were used to produce l-ribose from l-arabinose via l-ribulose with high productivity. However, a rate-limiting step in the two enzyme systems is the conversion of l-ribulose to l-ribose using l-ribose isomerase (7, 12) or Mannose-6-Phosphate isomerase (23-25). Thus, biotechnological production of l-ribose has been focused on these enzymes. Mannose-6-Phosphate isomerase from G. thermodenitrificans exhibits the highest activity to date for l-ribose production. Greater efficiency can be attained only through the discovery or synthesis of l-ribose-producing enzymes with higher kcat/Km. Increases in the kcat/Km ratio can be realized by genetic improvements via directed evolution and by structural modification of the determinant residues at or near the active site, based on homology models or the determined structure of the enzymes. In this study, the activities of a recombinant Mannose-6-Phosphate isomerase from Thermus thermophilus with different metal ions, pHs, and temperatures for l-ribulose isomerization and its substrate specificities for various aldoses and ketoses were characterized. Mutational analyses were performed with predicted active-site residues obtained from homology studies; the R142N mutant was selected as an effective l-ribose producer. The specific activity, kcat/Km, and conversion for l-ribulose using the R142N mutant were determined.
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characterization of a Mannose 6 Phosphate isomerase from thermus thermophilus and increased l ribose production by its r142n mutant
Applied and Environmental Microbiology, 2011Co-Authors: Soo Jin Yeom, Eunsun Seo, Bina Kim, Yeongsu KimAbstract:ABSTRACT An uncharacterized gene from Thermus thermophilus, thought to encode a Mannose-6-Phosphate isomerase, was cloned and expressed in Escherichia coli. The maximal activity of the recombinant enzyme for l-ribulose isomerization was observed at pH 7.0 and 75°C in the presence of 0.5 mM Cu2+. Among all of the pentoses and hexoses evaluated, the enzyme exhibited the highest activity for the conversion of l-ribulose to l-ribose, a potential starting material for many l-nucleoside-based pharmaceutical compounds. The active-site residues, predicted according to a homology-based model, were separately replaced with Ala. The residue at position 142 was correlated with an increase in l-ribulose isomerization activity. The R142N mutant showed the highest activity among mutants modified with Ala, Glu, Tyr, Lys, Asn, or Gln. The specific activity and catalytic efficiency (kcat/Km) for l-ribulose using the R142N mutant were 1.4- and 1.6-fold higher than those of the wild-type enzyme, respectively. The kcat/Km of the R142N mutant was 3.8-fold higher than that of Geobacillus thermodenitrificans Mannose-6-Phosphate isomerase, which exhibited the highest activity to date for the previously reported kcat/Km. The R142N mutant enzyme produced 213 g/liter l-ribose from 300 g/liter l-ribulose for 2 h, with a volumetric productivity of 107 g liter−1 h−1, which was 1.5-fold higher than that of the wild-type enzyme.
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substrate specificity of a Mannose 6 Phosphate isomerase from bacillus subtilis and its application in the production of l ribose
Applied and Environmental Microbiology, 2009Co-Authors: Soo Jin Yeom, Namhee Kim, Chang-su ParkAbstract:The uncharacterized gene previously proposed as a Mannose-6-Phosphate isomerase from Bacillus subtilis was cloned and expressed in Escherichia coli. The maximal activity of the recombinant enzyme was observed at pH 7.5 and 40°C in the presence of 0.5 mM Co2+. The isomerization activity was specific for aldose substrates possessing hydroxyl groups oriented in the same direction at the C-2 and C-3 positions, such as the d and l forms of ribose, lyxose, talose, Mannose, and allose. The enzyme exhibited the highest activity for l-ribulose among all pentoses and hexoses. Thus, l-ribose, as a potential starting material for many l-nucleoside-based pharmaceutical compounds, was produced at 213 g/liter from 300-g/liter l-ribulose by Mannose-6-Phosphate isomerase at 40°C for 3 h, with a conversion yield of 71% and a volumetric productivity of 71 g liter−1 h−1.
Jason Wong - One of the best experts on this subject based on the ideXlab platform.
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a multicentre randomized double blind trial of the safety and efficacy of Mannose 6 Phosphate in patients having zone ii flexor tendon repairs
Journal of Hand Surgery (European Volume), 2015Co-Authors: Vivien C Lees, D Warwick, P Gillespie, A P Brown, M A Akhavani, D Dewer, D Boyce, Stephanos Papanastasiou, Raj Ragoowansi, Jason WongAbstract:The safety, tolerability and preliminary efficacy of Mannose 6-Phosphate in enhancing the outcome in Zone II flexor tendon repair was studied in a multicentre parallel double-blinded randomized controlled trial. Eight UK teaching hospitals were involved in treating repaired flexor tendons with a single intraoperative intrathecal dose of 600 mM Mannose 6-Phosphate, with follow-up over 26 weeks. A total of 39 patients (Mannose 6-Phosphate, n = 20; standard care, n = 19) were randomized. Seven were excluded from the safety and tolerability analysis because of intraoperative findings and eight were excluded due to early dropout (n = 4) or tendon rupture (n = 4), leaving 24 (Mannose 6-Phosphate, n = 13; standard care, n = 11) for assessment of total active motion. The safety, tolerability and other side effects were comparable between the groups. There was no significant difference between the two groups in the total active motion at Week 26. We concluded that Mannose 6-Phosphate, although safe and tolerable, ...
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a multicentre randomized double blind trial of the safety and efficacy of Mannose 6 Phosphate in patients having zone ii flexor tendon repairs
Journal of Hand Surgery (European Volume), 2015Co-Authors: Vivien C Lees, D Warwick, P Gillespie, A P Brown, M A Akhavani, D Dewer, D Boyce, Stephanos Papanastasiou, Raj Ragoowansi, Jason WongAbstract:The safety, tolerability and preliminary efficacy of Mannose 6-Phosphate in enhancing the outcome in Zone II flexor tendon repair was studied in a multicentre parallel double-blinded randomized controlled trial. Eight UK teaching hospitals were involved in treating repaired flexor tendons with a single intraoperative intrathecal dose of 600 mM Mannose 6-Phosphate, with follow-up over 26 weeks. A total of 39 patients (Mannose 6-Phosphate, n = 20; standard care, n = 19) were randomized. Seven were excluded from the safety and tolerability analysis because of intraoperative findings and eight were excluded due to early dropout (n = 4) or tendon rupture (n = 4), leaving 24 (Mannose 6-Phosphate, n = 13; standard care, n = 11) for assessment of total active motion. The safety, tolerability and other side effects were comparable between the groups. There was no significant difference between the two groups in the total active motion at Week 26. We concluded that Mannose 6-Phosphate, although safe and tolerable, had no beneficial effect on finger range of motion after Zone II tendon division.Level of evidence 1b.