Nakamichi Yusuke, Shimada Naoki, Watanabe Masahiro, Fujii Tatsuya, Yaoi Katsuro, Matsuzawa Tomohiko
Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046, Japan.
Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, 2393 Ikenobe, Miki, Kita-gun, Kagawa 761-0701, Japan.
J Struct Biol. 2025 Jun;217(2):108213. doi: 10.1016/j.jsb.2025.108213. Epub 2025 May 23.
Xeg5A from Aspergillus oryzae belongs to glycoside hydrolase family 5 subfamily 4. This enzyme has been characterized as a xyloglucan-specific endo-β-1,4-glucanase (xyloglucanase) that cleaves the main chain of xyloglucan at both unbranched and xylosylated glucosyl residues in an endo-processive mode of action. X-ray crystallography revealed that Xeg5A is a tri-modular enzyme composed of a catalytic, an Ig-like, and a C-terminal CBM46-like domains. Xeg5A structures complexed with branched xyloglucan oligosaccharides at subsites -4 to +4 showed that the recognition of xyloglucan side-chain moieties is important for Xeg5A activity. The crystal structure also provided structural insights into the role of the CBM46-like domain in contributing to regiospecificity and, possibly, processivity.
