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1e5b

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{{STRUCTURE_1e5b| PDB=1e5b | SCENE= }}
{{STRUCTURE_1e5b| PDB=1e5b | SCENE= }}
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'''INTERNAL XYLAN BINDING DOMAIN FROM C. FIMI XYN10A, R262G MUTANT'''
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===INTERNAL XYLAN BINDING DOMAIN FROM C. FIMI XYN10A, R262G MUTANT===
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==Overview==
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The interactions of proteins with polysaccharides play a key role in the microbial hydrolysis of cellulose and xylan, the most abundant organic molecules in the biosphere, and are thus pivotal to the recycling of photosynthetically fixed carbon. Enzymes that attack these recalcitrant polymers have a modular structure comprising catalytic modules and non-catalytic carbohydrate-binding modules (CBMs). The largest prokaryotic CBM family, CBM2, contains members that bind cellulose (CBM2a) and xylan (CBM2b), respectively. A possible explanation for the different ligand specificity of CBM2b is that one of the surface tryptophans involved in the protein-carbohydrate interaction is rotated by 90 degrees compared with its position in CBM2a (thus matching the structure of the binding site to the helical secondary structure of xylan), which may be promoted by a single amino acid difference between the two families. Here we show that by mutation of this single residue (Arg-262--&gt;Gly), a CBM2b xylan-binding module completely loses its affinity for xylan and becomes a cellulose-binding module. The structural effect of the mutation has been revealed using NMR spectroscopy, which confirms that Trp-259 rotates 90 degrees to lie flat against the protein surface. Except for this one residue, the mutation only results in minor changes to the structure. The mutated protein interacts with cellulose using the same residues that the wild-type CBM2b uses to interact with xylan, suggesting that the recognition is of the secondary structure of the polysaccharide rather than any specific recognition of the absence or presence of functional groups.
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(as it appears on PubMed at http://www.pubmed.gov), where 10973978 is the PubMed ID number.
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{{ABSTRACT_PUBMED_10973978}}
==About this Structure==
==About this Structure==
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1E5B is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Cellulomonas_fimi Cellulomonas fimi]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1E5B OCA].
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1E5B is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Cellulomonas_fimi Cellulomonas fimi]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1E5B OCA].
==Reference==
==Reference==
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[[Category: Xylan binding domain]]
[[Category: Xylan binding domain]]
[[Category: Xylanase]]
[[Category: Xylanase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 14:40:47 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 00:10:17 2008''

Revision as of 21:10, 30 June 2008

Image:1e5b.png

Template:STRUCTURE 1e5b

INTERNAL XYLAN BINDING DOMAIN FROM C. FIMI XYN10A, R262G MUTANT

Template:ABSTRACT PUBMED 10973978

About this Structure

1E5B is a Single protein structure of sequence from Cellulomonas fimi. Full experimental information is available from OCA.

Reference

The structural basis for the ligand specificity of family 2 carbohydrate-binding modules., Simpson PJ, Xie H, Bolam DN, Gilbert HJ, Williamson MP, J Biol Chem. 2000 Dec 29;275(52):41137-42. PMID:10973978

Page seeded by OCA on Tue Jul 1 00:10:17 2008

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