1om0
From Proteopedia
(New page: 200px<br /><applet load="1om0" size="450" color="white" frame="true" align="right" spinBox="true" caption="1om0, resolution 1.80Å" /> '''crystal structure of...) |
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| - | [[Image:1om0.jpg|left|200px]]<br /><applet load="1om0" size=" | + | [[Image:1om0.jpg|left|200px]]<br /><applet load="1om0" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1om0, resolution 1.80Å" /> | caption="1om0, resolution 1.80Å" /> | ||
'''crystal structure of xylanase inhibitor protein (XIP-I) from wheat'''<br /> | '''crystal structure of xylanase inhibitor protein (XIP-I) from wheat'''<br /> | ||
==Overview== | ==Overview== | ||
| - | A novel class of proteinaceous inhibitors exhibiting specificity towards | + | A novel class of proteinaceous inhibitors exhibiting specificity towards microbial xylanases has recently been discovered in cereals. The three-dimensional structure of xylanase inhibitor protein I (XIP-I) from wheat (Triticum aestivum, var. Soisson) was determined by X-ray crystallography at 1.8 A (1 A=0.1 nm) resolution. The inhibitor possesses a (beta/alpha)(8) barrel fold and has structural features typical of glycoside hydrolase family 18, namely two consensus regions, approximately corresponding to the third and fourth barrel strands, and two non-proline cis -peptide bonds, Ser(36)-Phe and Trp(256)-Asp (in XIP-I numbering). However, detailed structural analysis of XIP-I revealed several differences in the region homologous with the active site of chitinases. The catalytic glutamic acid residue of family 18 chitinases [Glu(127) in hevamine, a chitinase/lysozyme from the rubber tree (Hevea brasiliensis)] is conserved in the structure of the inhibitor (Glu(128)), but its side chain is fully engaged in salt bridges with two neighbouring arginine residues. Gly(81), located in subsite -1 of hevamine, where the reaction intermediate is formed, is replaced by Tyr(80) in XIP-I. The tyrosine side chain fills the subsite area and makes a strong hydrogen bond with the side chain of Glu(190) located at the opposite side of the cleft, preventing access of the substrate to the catalytic glutamic acid. The structural differences in the inhibitor cleft structure probably account for the lack of activity of XIP-I towards chitin. |
==About this Structure== | ==About this Structure== | ||
| - | 1OM0 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Triticum_aestivum Triticum aestivum] with NDG, NAG and EDO as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1OM0 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Triticum_aestivum Triticum aestivum] with <scene name='pdbligand=NDG:'>NDG</scene>, <scene name='pdbligand=NAG:'>NAG</scene> and <scene name='pdbligand=EDO:'>EDO</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1OM0 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: beta-alpha barrel]] | [[Category: beta-alpha barrel]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:19:13 2008'' |
Revision as of 12:19, 21 February 2008
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crystal structure of xylanase inhibitor protein (XIP-I) from wheat
Overview
A novel class of proteinaceous inhibitors exhibiting specificity towards microbial xylanases has recently been discovered in cereals. The three-dimensional structure of xylanase inhibitor protein I (XIP-I) from wheat (Triticum aestivum, var. Soisson) was determined by X-ray crystallography at 1.8 A (1 A=0.1 nm) resolution. The inhibitor possesses a (beta/alpha)(8) barrel fold and has structural features typical of glycoside hydrolase family 18, namely two consensus regions, approximately corresponding to the third and fourth barrel strands, and two non-proline cis -peptide bonds, Ser(36)-Phe and Trp(256)-Asp (in XIP-I numbering). However, detailed structural analysis of XIP-I revealed several differences in the region homologous with the active site of chitinases. The catalytic glutamic acid residue of family 18 chitinases [Glu(127) in hevamine, a chitinase/lysozyme from the rubber tree (Hevea brasiliensis)] is conserved in the structure of the inhibitor (Glu(128)), but its side chain is fully engaged in salt bridges with two neighbouring arginine residues. Gly(81), located in subsite -1 of hevamine, where the reaction intermediate is formed, is replaced by Tyr(80) in XIP-I. The tyrosine side chain fills the subsite area and makes a strong hydrogen bond with the side chain of Glu(190) located at the opposite side of the cleft, preventing access of the substrate to the catalytic glutamic acid. The structural differences in the inhibitor cleft structure probably account for the lack of activity of XIP-I towards chitin.
About this Structure
1OM0 is a Single protein structure of sequence from Triticum aestivum with , and as ligands. Full crystallographic information is available from OCA.
Reference
Structural analysis of xylanase inhibitor protein I (XIP-I), a proteinaceous xylanase inhibitor from wheat (Triticum aestivum, var. Soisson)., Payan F, Flatman R, Porciero S, Williamson G, Juge N, Roussel A, Biochem J. 2003 Jun 1;372(Pt 2):399-405. PMID:12617724
Page seeded by OCA on Thu Feb 21 14:19:13 2008
Categories: Single protein | Triticum aestivum | Flatman, R. | Juge, N. | Payan, F. | Porciero, S. | Roussel, A. | Williamson, G. | EDO | NAG | NDG | Beta-alpha barrel
