Structural insights into the inhibition mechanism of glucosidase inhibitors toward kojibiose hydrolase belonging to glycoside hydrolase family 65.

Nakamura, Shuntaro; Miyazaki, Takatsugu

Glycoside hydrolase family 65 (GH65) includes glycoside hydrolases active on various α-glucosides. We previously demonstrated that the GH65 enzyme from Flavobacterium johnsoniae (FjGH65A) is a kojibiose hydrolase and determined its 3-dimensional structure. In this study, the effects of glucosidase inhibitors on FjGH65A and their complex structures were analyzed to elucidate their inhibition mechanism. FjGH65A was competitively inhibited by 1-deoxynojirimycin (DNJ) and noncompetitively inhibited by castanospermine (CSP) with K i values of 2.95 and 3.69 µ m , respectively. The crystal structures of FjGH65A complexed with the inhibitors indicated that DNJ was bound to subsite −1 of FjGH65A, while CSP was bound to subsites −1 and  1 of FjGH65A. Compared with the glucose complex structure, the conformation of Tyr337 was changed in the CSP complex structure. These results provide new structural insights into the mechanism of inhibition against GH65 α-glucoside hydrolases.

GLYCOSIDASES; GLUCOSIDASE inhibitors; CRYSTAL structure; HYDROLASES; FLAVOBACTERIUM; GLUCOSIDASES

Bioscience, Biotechnology & Biochemistry, 2025, Vol 89, Issue 1, p72

0916-8451

Academic Journal

10.1093/bbb/zbae158