1aoh: Difference between revisions
New page: left|200px<br /><applet load="1aoh" size="450" color="white" frame="true" align="right" spinBox="true" caption="1aoh, resolution 1.7Å" /> '''SINGLE COHESIN DOMAIN... |
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[[Image:1aoh.gif|left|200px]]<br /><applet load="1aoh" size=" | [[Image:1aoh.gif|left|200px]]<br /><applet load="1aoh" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1aoh, resolution 1.7Å" /> | caption="1aoh, resolution 1.7Å" /> | ||
'''SINGLE COHESIN DOMAIN FROM THE SCAFFOLDING PROTEIN CIPA OF THE CLOSTRIDIUM THERMOCELLUM CELLULOSOME'''<br /> | '''SINGLE COHESIN DOMAIN FROM THE SCAFFOLDING PROTEIN CIPA OF THE CLOSTRIDIUM THERMOCELLUM CELLULOSOME'''<br /> | ||
==Overview== | ==Overview== | ||
The quaternary organization of the cellulosome, a multi-enzymatic | The quaternary organization of the cellulosome, a multi-enzymatic extracellular complex produced by cellulolytic bacteria, depends on specific interactions between dockerin domains, double EF-hand subunits carried by the catalytic components, and cohesin domains, individual receptor subunits linearly arranged within a non-catalytic scaffolding polypeptide. Cohesin-dockerin complexes with distinct specificities are also thought to mediate the attachment of cellulosomes to the cell membrane.We report here the crystal structure of a single cohesin domain from the scaffolding protein of Clostridium thermocellum. The cohesin domain folds into a nine-stranded beta-sandwich with an overall "jelly roll" topology, similar to that observed in bacterial cellulose-binding domains. Surface-exposed patches of conserved residues promote extensive intermolecular contacts in the crystal, and suggest a possible binding target for the EF-hand pair of the cognate dockerin domain. Comparative studies of cohesin domains indicate that, in spite of low sequence similarities and different functional roles, all cohesin domains share a common nine-stranded beta-barrel fold stabilized by a conserved hydrophobic core.The formation of stable cohesin-dockerin complexes requires the presence of Ca2+. However, the structure of the cohesin domain reported here reveals no obvious Ca2+-binding site, and previous experiments have failed to detect high affinity binding of Ca2+ to the unliganded dockerin domain of endoglucanase CelD. Based on structural and biochemical evidence, we propose a model of the cohesin-dockerin complex in which the dockerin domain requires complexation with its cohesin partner for protein stability and high-affinity Ca2+ binding. | ||
==About this Structure== | ==About this Structure== | ||
1AOH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Clostridium_thermocellum Clostridium thermocellum]. Full crystallographic information is available from [http:// | 1AOH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Clostridium_thermocellum Clostridium thermocellum]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1AOH OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Clostridium thermocellum]] | [[Category: Clostridium thermocellum]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Alzari, P | [[Category: Alzari, P M.]] | ||
[[Category: Tavares, G.]] | [[Category: Tavares, G.]] | ||
[[Category: b-barrel]] | [[Category: b-barrel]] | ||
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[[Category: cellulosome subunit]] | [[Category: cellulosome subunit]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:46:43 2008'' | ||
Revision as of 12:46, 21 February 2008
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SINGLE COHESIN DOMAIN FROM THE SCAFFOLDING PROTEIN CIPA OF THE CLOSTRIDIUM THERMOCELLUM CELLULOSOME
OverviewOverview
The quaternary organization of the cellulosome, a multi-enzymatic extracellular complex produced by cellulolytic bacteria, depends on specific interactions between dockerin domains, double EF-hand subunits carried by the catalytic components, and cohesin domains, individual receptor subunits linearly arranged within a non-catalytic scaffolding polypeptide. Cohesin-dockerin complexes with distinct specificities are also thought to mediate the attachment of cellulosomes to the cell membrane.We report here the crystal structure of a single cohesin domain from the scaffolding protein of Clostridium thermocellum. The cohesin domain folds into a nine-stranded beta-sandwich with an overall "jelly roll" topology, similar to that observed in bacterial cellulose-binding domains. Surface-exposed patches of conserved residues promote extensive intermolecular contacts in the crystal, and suggest a possible binding target for the EF-hand pair of the cognate dockerin domain. Comparative studies of cohesin domains indicate that, in spite of low sequence similarities and different functional roles, all cohesin domains share a common nine-stranded beta-barrel fold stabilized by a conserved hydrophobic core.The formation of stable cohesin-dockerin complexes requires the presence of Ca2+. However, the structure of the cohesin domain reported here reveals no obvious Ca2+-binding site, and previous experiments have failed to detect high affinity binding of Ca2+ to the unliganded dockerin domain of endoglucanase CelD. Based on structural and biochemical evidence, we propose a model of the cohesin-dockerin complex in which the dockerin domain requires complexation with its cohesin partner for protein stability and high-affinity Ca2+ binding.
About this StructureAbout this Structure
1AOH is a Single protein structure of sequence from Clostridium thermocellum. Full crystallographic information is available from OCA.
ReferenceReference
The crystal structure of a type I cohesin domain at 1.7 A resolution., Tavares GA, Beguin P, Alzari PM, J Mol Biol. 1997 Oct 31;273(3):701-13. PMID:9402065
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