1OM0

crystal structure of xylanase inhibitor protein (XIP-I) from wheat

1OM0 の概要

• エントリーDOI: 10.2210/pdb1om0/pdb
• 分子名称: Xylanase Inhibitor Protein I, 2-acetamido-2-deoxy-beta-D-glucopyranose, 1,2-ETHANEDIOL, ... (4 entities in total)
• 機能のキーワード: beta-alpha barrel, sugar binding protein
• 由来する生物種: Triticum aestivum (bread wheat)
• 細胞内の位置: Secreted (Potential): Q8L5C6
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 31325.02

構造登録者

Payan, F.,Flatman, R.,Porciero, S.,Williamson, G.,Juge, N.,Roussel, A. (登録日: 2003-02-24, 公開日: 2003-06-03, 最終更新日: 2024-10-23)

主引用文献

Payan, F.,Flatman, R.,Porciero, S.,Williamson, G.,Juge, N.,Roussel, A.
Structural analysis of xylanase inhibitor protein I (XIP-I), a proteinaceous xylanase inhibitor from wheat (Triticum aestivum, var. Soisson).
Biochem.J., 372:399-405, 2003

PubMed Abstract: 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.

PubMed: 12617724
DOI: 10.1042/BJ20021802

実験手法

X-RAY DIFFRACTION (1.8 Å)