The Experts below are selected from a list of 51 Experts worldwide ranked by ideXlab platform
Tyrrell Conway - One of the best experts on this subject based on the ideXlab platform.
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glycogen and maltose utilization by escherichia coli o157 h7 in the mouse intestine
Infection and Immunity, 2008Co-Authors: Shari A Jones, Mathias Jorgensen, Fatema Z Chowdhury, Rosalie Rodgers, James Hartline, Mary P Leatham, Carsten Struve, Karen Angeliki Krogfelt, Paul S Cohen, Tyrrell ConwayAbstract:In nature, the nutrients that support bacterial growth are rarely available continuously and are almost always present in limiting amounts, leading to the idea that bacterial existence is one of feast or famine (24). Others have proposed the existence of an in-between state, namely hunger, which is defined by expression of carbon-scavenging systems (18). In the mammalian gastrointestinal tract (9), despite growing in a mucus layer rich in carbohydrates, lipids, and proteins (27), Escherichia coli apparently leads a scavenging lifestyle, using up to seven different sugars to support its colonization (7, 16). It is likely that the availability of one or more of its preferred nutrients in the intestine is limited and variable. Thus, for E. coli to cope with life in a nutrient-limiting environment where it is hungry or occasionally starving, we hypothesize that successful competition and persistence in the intestine requires intracellular energy stores. Glycogen is the primary carbon and energy storage molecule for enteric bacteria, including E. coli (5). The discovery of glycogen in E. coli is credited to Cedergren and Holme (6). In an early review of bacterial cell composition, it was Neidhardt who first suggested that glycogen degradation might be linked to energy metabolism (34). It is now well established that glycogen is the fundamental carbon and energy storage compound for many bacteria and plays a major role in long-term survival of the cell. Glycogen is synthesized during times when carbon is abundant but other nutrients are limiting (36). GlgA, glycogen synthase, is responsible for the transfer of the glucosyl unit from ADP-glucose to the growing glycogen polymer to form a new α-1,4-glucosidic linkage (37). GlgB is the branching enzyme that catalyzes formation of α-1,6-glucosidic linkages. GlgC, Glucose-1-Phosphate Adenylyltransferase, forms ADP-glucose from Glucose-1-Phosphate and ATP. GlgS is required for glycogen synthesis, its overproduction stimulates glycogen synthesis, and it is induced upon entry into stationary in an RpoS-dependent manner (21). However, GlgS has no defined role in glycogen synthesis, although its crystal structure suggests involvement in protein-protein interactions (25). Glycogen degradation occurs when carbon sources become limiting (13). GlgP, glycogen phosphorylase, catalyzes glycogen breakdown by removing glucose units from the polysaccharide. GlgX, glycogen debranching enzyme, hydrolyzes α-1,6-glucosidic linkages in limit dextrins generated by GlgP (12). In salmonellae, the role of glycogen metabolism in colonization and virulence is controversial, with one study suggesting a connection between glycogen storage and virulence (4) and another showing a minor role, at best (30). The contributions of glycogen synthesis and degradation to animal colonization have not been tested for E. coli. In support of the hypothesis that glycogen metabolism is important for colonization, we previously found that one of the genes involved in glycogen metabolism, glgS, is highly induced in E. coli MG1655 when growing on mucus, conditions that are thought to mimic nutrient availability in the intestine (7). Since glycogen breakdown involves maltose and maltodextrins as intermediates, we also thought to examine whether catabolism of exogenous maltose and maltodextrins supports colonization. This possibility seemed reasonable since maltose metabolism genes are also induced in E. coli MG1655 when growing on mucus (7). Maltose consists of two glucose molecules joined by an α-1,4 linkage; maltodextrins are longer glucose polymers. These sugars are most commonly derived from starch and glycogen. At least nine genes encode proteins that are involved in the utilization of maltose and maltodextrins in E. coli (29). The maltose-inducible porin for maltodextrin transport into the periplasm is encoded by lamB (46). The maltose/maltodextrin transporter is a high-affinity ABC system consisting of a periplasmic maltose-binding protein, encoded by malE, and a transport complex encoded by malF, malG, and malK (5). malQ (amylomaltase) and malP (maltodextrin phosphorylase) encode enzymes for maltose and maltodextrin catabolism, respectively. MalQ uses maltodextrins as maltose acceptors in a reaction that releases glucose, which enters glycolysis after being phosphorylated by glucokinase (5). MalP cleaves glucosyl residues from the nonreducing end of maltodextrins, forming α-Glucose-1-Phosphate, which enters glycolysis after conversion to glucose 6-phosphate by phosphoglucomutase (5). Mutants lacking MalQ cannot grow on maltose, whereas malP mutants can grow on maltose but not on maltodextrins (14). We previously identified several monosaccharides utilized during colonization of the mouse intestine by pathogenic E. coli EDL933 (16) and commensal E. coli MG1655 (7). Here, we explore the possibility that complex sugars, i.e., maltose, maltodextrin, and glycogen, support intestinal colonization. The results demonstrate that maltose, but not maltodextrin, is important for colonization of both pathogenic and commensal E. coli strains. In addition, glycogen synthesis and glycogen degradation are important for efficient intestinal colonization, suggesting a hunger or famine lifestyle for E. coli in the mouse intestine. The results increase our understanding of nutrient utilization in vivo and provide new insights into host-pathogen interactions.
Claire R. Shen - One of the best experts on this subject based on the ideXlab platform.
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Isobutanol production as an alternative metabolic sink to rescue the growth deficiency of the glycogen mutant of Synechococcus elongatus PCC 7942
Photosynthesis Research, 2014Co-Authors: Xiaoqian Li, Claire R. ShenAbstract:Glycogen synthesis initiated by Glucose-1-Phosphate Adenylyltransferase (glgC) represents a major carbon storage route in cyanobacteria which could divert a significant portion of assimilated carbon. Significant growth retardation in cyanobacteria with glgC knocked out (ΔglgC) has been reported in high light conditions. Here, we knocked out the glgC gene and analyzed its effects on carbon distribution in an isobutanol-producing strain of Synechococcus elongatus PCC7942 and its parental wild-type strain. We showed that isobutanol production was able to partially rescue the growth of ΔglgC mutant where the growth rescue effect positively correlated with the rate of isobutanol production. Using NaH(14)CO3 incorporation analysis, we observed a 28 % loss of total carbon fixation rate in the ΔglgC mutant compared to the wild-type. Upon expression of the isobutanol production pathway in ΔglgC mutant, the total carbon fixation rate was restored to the wild-type level. Furthermore, we showed that 52 % of the total carbon fixed was redirected into isobutanol biosynthesis in the ΔglgC mutant expressing enzymes for isobutanol production, which is 2.5 times higher than that of the wild-type expressing the same enzymes. These results suggest that biosynthesis of non-native product such as isobutanol can serve as a metabolic sink for replacing glycogen to rescue growth and restore carbon fixation rate. The rescue effect may further serve as a platform for cyanobacteria energy and carbon metabolism study.
Dietmar Schomburg - One of the best experts on this subject based on the ideXlab platform.
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Central carbon metabolism in S. solfataricus with flux distribution for growth on HCO3−.
2012Co-Authors: Thomas Ulas, Alexander S. Riemer, Melanie Zaparty, Bettina Siebers, Dietmar SchomburgAbstract:Solid arrows show the used pathways and their directions. Dashed arrows show available but not used pathways. Arrow size represents predicted flux though the pathways. Enzymes in this pathway: (1) glucose 1-dehydrogenase, (2) gluconolactonase, (3) gluconate dehydratase (4) 2-dehydro-3-deoxygluconokinase, (5) 2-dehydro-3-deoxy-phosphogluconate aldolase, (6) glyceraldehyde-3-phosphate dehydrogenase, (7) phosphoglycerate mutase, (8) phosphopyruvate hydratase, (9) pyruvate kinase, (10) pyruvate synthase, (11) citrate (Si)-synthase, (12) aconitate hydratase, (13) isocitrate dehydrogenase, (14) 2-oxoglutarate synthase, (15) succinate-CoA ligase, (16) succinate dehydrogenase, (17) fumarate hydratase, (18) malate dehydrogenase, (19) glucose 1-dehydrogenase, (20) galactonate dehydratase, (21) 2-keto-3-deoxygluconate aldolase, (22) aldehyde dehydrogenase, (23) glycerate kinase, (24) malate dehydrogenase, (25) phosphoenolpyruvate carboxykinase (GTP), (26) phosphoenolpyruvate carboxylase, ((27) pyruvate carboxylase, (28) triose-phosphate isomerase, (29) fructose-bisphosphate aldolase, (30) fructose-bisphosphatase, (31) glucose-6-phosphate isomerase, (32) beta-phosphoglucomutase, (33) Glucose-1-Phosphate Adenylyltransferase, (34) starch synthase, (35) glucan 1,4-alpha-glucosidase, (36) 6-phospho-3-hexuloisomerase, (37) 3-hexulose-6-phosphate synthase, (38) ribose-5-phosphate isomerase, (39) ribose-phosphate diphosphokinase, (40) transketolase, (41) transketolase, (42) sulfite reductase, (43) phosphoadenylyl-sulfate reductase, (44) sulfate Adenylyltransferase, (45) adenylyl-sulfate kinase, (46) 3′(2′),5′-bisphosphate nucleotidase, (47) phosphoglycerate kinase, (48) glyceraldehyde-3-phosphate dehydrogenase.
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Central carbon metabolism in S. solfataricus with flux distribution for growth on glucose.
2012Co-Authors: Thomas Ulas, Alexander S. Riemer, Melanie Zaparty, Bettina Siebers, Dietmar SchomburgAbstract:Solid arrows show the used pathways and their directions. Dashed arrows show available but not used pathways. Arrow size represents predicted flux though the pathways. Enzymes in this pathway: (1) glucose 1-dehydrogenase, (2) gluconolactonase, (3) gluconate dehydratase (4) 2-dehydro-3-deoxygluconokinase, (5) 2-dehydro-3-deoxy-phosphogluconate aldolase, (6) glyceraldehyde-3-phosphate dehydrogenase, (7) phosphoglycerate mutase, (8) phosphopyruvate hydratase, (9) pyruvate kinase, (10) pyruvate synthase, (11) citrate (Si)-synthase, (12) aconitate hydratase, (13) isocitrate dehydrogenase, (14) 2-oxoglutarate synthase, (15) succinate-CoA ligase, (16) succinate dehydrogenase, (17) fumarate hydratase, (18) malate dehydrogenase, (19) glucose 1-dehydrogenase, (20) galactonate dehydratase, (21) 2-keto-3-deoxygluconate aldolase, (22) aldehyde dehydrogenase, (23) glycerate kinase, (24) malate dehydrogenase, (25) phosphoenolpyruvate carboxykinase (GTP), (26) phosphoenolpyruvate carboxylase, (27) pyruvate carboxylase, (28) triose-phosphate isomerase, (29) fructose-bisphosphate aldolase, (30) fructose-bisphosphatase, (31) glucose-6-phosphate isomerase, (32) beta-phosphoglucomutase, (33) Glucose-1-Phosphate Adenylyltransferase, (34) starch synthase, (35) glucan 1,4-alpha-glucosidase, (36) 6-phospho-3-hexuloisomerase, (37) 3-hexulose-6-phosphate synthase, (38) ribose-5-phosphate isomerase, (39) ribose-phosphate diphosphokinase, (40) transketolase, (41) transketolase, (42) sulfite reductase, (43) phosphoadenylyl-sulfate reductase, (44) sulfate Adenylyltransferase, (45) adenylyl-sulfate kinase, (46) 3′(2′),5′-bisphosphate nucleotidase, (47) phosphoglycerate kinase, (48) glyceraldehyde-3-phosphate dehydrogenase.
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Central carbon metabolism in S. solfataricus with flux distribution for growth on phenol.
2012Co-Authors: Thomas Ulas, Alexander S. Riemer, Melanie Zaparty, Bettina Siebers, Dietmar SchomburgAbstract:Solid arrows show the used pathways and their directions. Dashed arrows show available but not used pathways. Arrow size represents predicted flux though the pathways. Enzymes in this pathway: (1) glucose 1-dehydrogenase, (2) gluconolactonase, (3) gluconate dehydratase (4) 2-dehydro-3-deoxygluconokinase, (5) 2-dehydro-3-deoxy-phosphogluconate aldolase, (6) glyceraldehyde-3-phosphate dehydrogenase, (7) phosphoglycerate mutase, (8) phosphopyruvate hydratase, (9) pyruvate kinase, (10) pyruvate synthase, (11) citrate (Si)-synthase, (12) aconitate hydratase, (13) isocitrate dehydrogenase, (14) 2-oxoglutarate synthase, (15) succinate-CoA ligase, (16) succinate dehydrogenase, (17) fumarate hydratase, (18) malate dehydrogenase, (19) glucose 1-dehydrogenase, (20) galactonate dehydratase, (21) 2-keto-3-deoxygluconate aldolase, (22) aldehyde dehydrogenase, (23) glycerate kinase, (24) malate dehydrogenase, (25) phosphoenolpyruvate carboxykinase (GTP), (26) phosphoenolpyruvate carboxylase, ((27) pyruvate carboxylase, (28) triose-phosphate isomerase, (29) fructose-bisphosphate aldolase, (30) fructose-bisphosphatase, (31) glucose-6-phosphate isomerase, (32) beta-phosphoglucomutase, (33) Glucose-1-Phosphate Adenylyltransferase, (34) starch synthase, (35) glucan 1,4-alpha-glucosidase, (36) 6-phospho-3-hexuloisomerase, (37) 3-hexulose-6-phosphate synthase, (38) ribose-5-phosphate isomerase, (39) ribose-phosphate diphosphokinase, (40) transketolase, (41) transketolase, (42) sulfite reductase, (43) phosphoadenylyl-sulfate reductase, (44) sulfate Adenylyltransferase, (45) adenylyl-sulfate kinase, (46) 3′(2′),5′-bisphosphate nucleotidase, (47) phosphoglycerate kinase, (48) glyceraldehyde-3-phosphate dehydrogenase, (49) phenol 2-monooxygenase, (50) catechol 2,3-dioxygenase, (51) 2-hydroxymuconate-semialdehyde hydrolase, (52) 2-oxopent-4-enoate hydratase, (53) 4-hydroxy-2-ketovalerate aldolase, (54) aldehyde dehydrogenase, (55) acetate-CoA ligase.
Shari A Jones - One of the best experts on this subject based on the ideXlab platform.
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glycogen and maltose utilization by escherichia coli o157 h7 in the mouse intestine
Infection and Immunity, 2008Co-Authors: Shari A Jones, Mathias Jorgensen, Fatema Z Chowdhury, Rosalie Rodgers, James Hartline, Mary P Leatham, Carsten Struve, Karen Angeliki Krogfelt, Paul S Cohen, Tyrrell ConwayAbstract:In nature, the nutrients that support bacterial growth are rarely available continuously and are almost always present in limiting amounts, leading to the idea that bacterial existence is one of feast or famine (24). Others have proposed the existence of an in-between state, namely hunger, which is defined by expression of carbon-scavenging systems (18). In the mammalian gastrointestinal tract (9), despite growing in a mucus layer rich in carbohydrates, lipids, and proteins (27), Escherichia coli apparently leads a scavenging lifestyle, using up to seven different sugars to support its colonization (7, 16). It is likely that the availability of one or more of its preferred nutrients in the intestine is limited and variable. Thus, for E. coli to cope with life in a nutrient-limiting environment where it is hungry or occasionally starving, we hypothesize that successful competition and persistence in the intestine requires intracellular energy stores. Glycogen is the primary carbon and energy storage molecule for enteric bacteria, including E. coli (5). The discovery of glycogen in E. coli is credited to Cedergren and Holme (6). In an early review of bacterial cell composition, it was Neidhardt who first suggested that glycogen degradation might be linked to energy metabolism (34). It is now well established that glycogen is the fundamental carbon and energy storage compound for many bacteria and plays a major role in long-term survival of the cell. Glycogen is synthesized during times when carbon is abundant but other nutrients are limiting (36). GlgA, glycogen synthase, is responsible for the transfer of the glucosyl unit from ADP-glucose to the growing glycogen polymer to form a new α-1,4-glucosidic linkage (37). GlgB is the branching enzyme that catalyzes formation of α-1,6-glucosidic linkages. GlgC, Glucose-1-Phosphate Adenylyltransferase, forms ADP-glucose from Glucose-1-Phosphate and ATP. GlgS is required for glycogen synthesis, its overproduction stimulates glycogen synthesis, and it is induced upon entry into stationary in an RpoS-dependent manner (21). However, GlgS has no defined role in glycogen synthesis, although its crystal structure suggests involvement in protein-protein interactions (25). Glycogen degradation occurs when carbon sources become limiting (13). GlgP, glycogen phosphorylase, catalyzes glycogen breakdown by removing glucose units from the polysaccharide. GlgX, glycogen debranching enzyme, hydrolyzes α-1,6-glucosidic linkages in limit dextrins generated by GlgP (12). In salmonellae, the role of glycogen metabolism in colonization and virulence is controversial, with one study suggesting a connection between glycogen storage and virulence (4) and another showing a minor role, at best (30). The contributions of glycogen synthesis and degradation to animal colonization have not been tested for E. coli. In support of the hypothesis that glycogen metabolism is important for colonization, we previously found that one of the genes involved in glycogen metabolism, glgS, is highly induced in E. coli MG1655 when growing on mucus, conditions that are thought to mimic nutrient availability in the intestine (7). Since glycogen breakdown involves maltose and maltodextrins as intermediates, we also thought to examine whether catabolism of exogenous maltose and maltodextrins supports colonization. This possibility seemed reasonable since maltose metabolism genes are also induced in E. coli MG1655 when growing on mucus (7). Maltose consists of two glucose molecules joined by an α-1,4 linkage; maltodextrins are longer glucose polymers. These sugars are most commonly derived from starch and glycogen. At least nine genes encode proteins that are involved in the utilization of maltose and maltodextrins in E. coli (29). The maltose-inducible porin for maltodextrin transport into the periplasm is encoded by lamB (46). The maltose/maltodextrin transporter is a high-affinity ABC system consisting of a periplasmic maltose-binding protein, encoded by malE, and a transport complex encoded by malF, malG, and malK (5). malQ (amylomaltase) and malP (maltodextrin phosphorylase) encode enzymes for maltose and maltodextrin catabolism, respectively. MalQ uses maltodextrins as maltose acceptors in a reaction that releases glucose, which enters glycolysis after being phosphorylated by glucokinase (5). MalP cleaves glucosyl residues from the nonreducing end of maltodextrins, forming α-Glucose-1-Phosphate, which enters glycolysis after conversion to glucose 6-phosphate by phosphoglucomutase (5). Mutants lacking MalQ cannot grow on maltose, whereas malP mutants can grow on maltose but not on maltodextrins (14). We previously identified several monosaccharides utilized during colonization of the mouse intestine by pathogenic E. coli EDL933 (16) and commensal E. coli MG1655 (7). Here, we explore the possibility that complex sugars, i.e., maltose, maltodextrin, and glycogen, support intestinal colonization. The results demonstrate that maltose, but not maltodextrin, is important for colonization of both pathogenic and commensal E. coli strains. In addition, glycogen synthesis and glycogen degradation are important for efficient intestinal colonization, suggesting a hunger or famine lifestyle for E. coli in the mouse intestine. The results increase our understanding of nutrient utilization in vivo and provide new insights into host-pathogen interactions.
Xiaoqian Li - One of the best experts on this subject based on the ideXlab platform.
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Isobutanol production as an alternative metabolic sink to rescue the growth deficiency of the glycogen mutant of Synechococcus elongatus PCC 7942
Photosynthesis Research, 2014Co-Authors: Xiaoqian Li, Claire R. ShenAbstract:Glycogen synthesis initiated by Glucose-1-Phosphate Adenylyltransferase (glgC) represents a major carbon storage route in cyanobacteria which could divert a significant portion of assimilated carbon. Significant growth retardation in cyanobacteria with glgC knocked out (ΔglgC) has been reported in high light conditions. Here, we knocked out the glgC gene and analyzed its effects on carbon distribution in an isobutanol-producing strain of Synechococcus elongatus PCC7942 and its parental wild-type strain. We showed that isobutanol production was able to partially rescue the growth of ΔglgC mutant where the growth rescue effect positively correlated with the rate of isobutanol production. Using NaH(14)CO3 incorporation analysis, we observed a 28 % loss of total carbon fixation rate in the ΔglgC mutant compared to the wild-type. Upon expression of the isobutanol production pathway in ΔglgC mutant, the total carbon fixation rate was restored to the wild-type level. Furthermore, we showed that 52 % of the total carbon fixed was redirected into isobutanol biosynthesis in the ΔglgC mutant expressing enzymes for isobutanol production, which is 2.5 times higher than that of the wild-type expressing the same enzymes. These results suggest that biosynthesis of non-native product such as isobutanol can serve as a metabolic sink for replacing glycogen to rescue growth and restore carbon fixation rate. The rescue effect may further serve as a platform for cyanobacteria energy and carbon metabolism study.