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Journal of Bacteriology
Devillard, E., MAPLE Research Initiative, Department of Animal Sciences, Ohio State University, Columbus, OH, United States
Goodheart, D.B., MAPLE Research Initiative, Department of Animal Sciences, Ohio State University, Columbus, OH, United States
Karnati, S.K.R., MAPLE Research Initiative, Department of Animal Sciences, Ohio State University, Columbus, OH, United States
Bayer, E.A., Weizmann Research Institute, Rehovot, Israel
Lamed, R., Dept. of Molec. Microbiol./Biotech., Aviv University, Ramat Aviv, Israel
Miron, J., Volcani Research Institute, Bet Dagan, Israel
Nelson, K.E., Institute for Genomic Research, Rockville, MD, United States, N. American Consortium for Genomics, Columbus, OH, United States
Morrison, M., MAPLE Research Initiative, Department of Animal Sciences, Ohio State University, Columbus, OH, United States, N. American Consortium for Genomics, Columbus, OH, United States, MAPLE Research Program, Department of Animal Sciences, Ohio State University, Columbus, OH 43210, United States
The cellulolytic bacterium Ruminococcus albus 8 adheres tightly to cellulose, but the molecular biology underpinning this process is not well characterized. Subtractive enrichment procedures were used to isolate mutants of R. albus 8 that are defective in adhesion to cellulose. Adhesion of the mutant strains was reduced 50% compared to that observed with the wild-type strain, and cellulose solubilization was also shown to be slower in these mutant strains, suggesting that bacterial adhesion and cellulose solubilization are inextricably linked. Two-dimensional polyacrylamide gel electrophoresis showed that all three mutants studied were impaired in the production of two high-molecular-mass, cell-bound polypeptides when they were cultured with either cellobiose or cellulose. The identities of these proteins were determined by a combination of mass spectrometry methods and genome sequence data for R. albus 8. One of the polypeptides is a family 9 glycoside hydrolase (Cel9B), and the other is a family 48 glycoside hydrolase (Cel48A). Both Cel9B and Cel48A possess a modular architecture, Cel9B possesses features characteristic of the B2 (or theme D) group of family 9 glycoside hydrolases, and Cel48A is structurally similar to the processive endocellulases CelF and CelS from Clostridium cellulolyticum and Clostridium thermocellum, respectively. Both Cel9B and Cel48A could be recovered by cellulose affinity procedures, but neither Cel9B nor Cel48A contains a dockerin, suggesting that these polypeptides are retained on the bacterial cell surface, and recovery by cellulose affinity procedures did not involve a clostridium-like cellulosome complex. Instead, both proteins possess a single copy of a novel X module with an unknown function at the C terminus. Such X modules are also present in several other R. albus glycoside hydrolases and are phylogentically distinct from the fibronectin III-like and X modules identified so far in other cellulolytic bacteria.
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Ruminococcus albus 8 Mutants Defective in Cellulose Degradation Are Deficient in Two Processive Endocellulases, Cel48A and Cel9B, Both of Which Possess a Novel Modular Architecture
186
Devillard, E., MAPLE Research Initiative, Department of Animal Sciences, Ohio State University, Columbus, OH, United States
Goodheart, D.B., MAPLE Research Initiative, Department of Animal Sciences, Ohio State University, Columbus, OH, United States
Karnati, S.K.R., MAPLE Research Initiative, Department of Animal Sciences, Ohio State University, Columbus, OH, United States
Bayer, E.A., Weizmann Research Institute, Rehovot, Israel
Lamed, R., Dept. of Molec. Microbiol./Biotech., Aviv University, Ramat Aviv, Israel
Miron, J., Volcani Research Institute, Bet Dagan, Israel
Nelson, K.E., Institute for Genomic Research, Rockville, MD, United States, N. American Consortium for Genomics, Columbus, OH, United States
Morrison, M., MAPLE Research Initiative, Department of Animal Sciences, Ohio State University, Columbus, OH, United States, N. American Consortium for Genomics, Columbus, OH, United States, MAPLE Research Program, Department of Animal Sciences, Ohio State University, Columbus, OH 43210, United States
Ruminococcus albus 8 Mutants Defective in Cellulose Degradation Are Deficient in Two Processive Endocellulases, Cel48A and Cel9B, Both of Which Possess a Novel Modular Architecture
The cellulolytic bacterium Ruminococcus albus 8 adheres tightly to cellulose, but the molecular biology underpinning this process is not well characterized. Subtractive enrichment procedures were used to isolate mutants of R. albus 8 that are defective in adhesion to cellulose. Adhesion of the mutant strains was reduced 50% compared to that observed with the wild-type strain, and cellulose solubilization was also shown to be slower in these mutant strains, suggesting that bacterial adhesion and cellulose solubilization are inextricably linked. Two-dimensional polyacrylamide gel electrophoresis showed that all three mutants studied were impaired in the production of two high-molecular-mass, cell-bound polypeptides when they were cultured with either cellobiose or cellulose. The identities of these proteins were determined by a combination of mass spectrometry methods and genome sequence data for R. albus 8. One of the polypeptides is a family 9 glycoside hydrolase (Cel9B), and the other is a family 48 glycoside hydrolase (Cel48A). Both Cel9B and Cel48A possess a modular architecture, Cel9B possesses features characteristic of the B2 (or theme D) group of family 9 glycoside hydrolases, and Cel48A is structurally similar to the processive endocellulases CelF and CelS from Clostridium cellulolyticum and Clostridium thermocellum, respectively. Both Cel9B and Cel48A could be recovered by cellulose affinity procedures, but neither Cel9B nor Cel48A contains a dockerin, suggesting that these polypeptides are retained on the bacterial cell surface, and recovery by cellulose affinity procedures did not involve a clostridium-like cellulosome complex. Instead, both proteins possess a single copy of a novel X module with an unknown function at the C terminus. Such X modules are also present in several other R. albus glycoside hydrolases and are phylogentically distinct from the fibronectin III-like and X modules identified so far in other cellulolytic bacteria.
Scientific Publication
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