Molecular arrangements that accompany binding of rice xylanase inhibitor protein OsXIP and the Rhizopus oryzae GH11 xylanase RXyn2.

ABSTRACT: Plants have evolved xylanase inhibitor proteins as part of their defense mechanisms against phytopathogens. The rice xylanase inhibitor protein (OsXIP) is structurally similar to GH18 chitinase and homologous to wheat XIP-type inhibitor (XIP-I), which inhibits both GH10 and GH11 xylanases. Various inhibition and interaction analyses showed that OsXIP competitively inhibits the hydrolytic activity of GH11 xylanase RXyn2, but not the activity of GH10 xylanase RXyn1 from Rhizopus oryzae. The crystal structure of the OsXIP/RXyn2 complex showed that OsXIP, which has a (β/α)₈-barrel fold, extrudes the loop between α4 and β5 (Lα4β5_OsXIP) and inserts the loop into the xylotriose binding site (-3 to -1 subsite) formed by the inner β-sheet (palm) of RXyn2 jelly roll. The guanid

SUBMITTER: Ohnuma T 

PROVIDER: S-EPMC12329526 | biostudies-literature | 2025 Jun

REPOSITORIES: biostudies-literature