Structural basis for broad substrate specificity in higher plant beta-D-glucan glucohydrolases
- Author(s)
- Hrmova, M; De Gori, R; Smith, BJ; Fairweather, JK; Driguez, H; Varghese, JN; Fincher, GB;
- Details
- Publication Year 2002-05,Volume 14,Issue #5,Page 1033-1052
- Journal Title
- PLANT CELL
- Publication Type
- Journal Article
- Abstract
- Family 3 beta-D-glucan glucohydrolases are distributed widely in higher plants. The enzymes catalyze the hydrolytic removal of beta-D-glucosyl residues from nonreducing termini of a range of beta-D-glucans and beta-D-oligoglucosides. Their broad specificity can be explained by x-ray crystallographic data obtained from a barley beta-D-glucan glucohydrolase in complex with nonhydrolyzable S-glycoside substrate analogs and by molecular modeling of enzyme/substrate complexes. The glucosyl residue that occupies binding subsite -1 is locked tightly into a fixed position through extensive hydrogen bonding with six amino acid residues near the bottom of an active site pocket. In contrast, the glucosyl residue at subsite +1 is located between two Trip residues at the entrance of the pocket, where it is constrained less tightly. The relative flexibility of binding at subsite +1, coupled with the projection of the remainder of bound substrate away from the enzyme's surface, means that the overall active site can accommodate a range of substrates with variable spatial dispositions of adjacent beta-D-glucosyl residues. The broad specificity for glycosidic linkage type enables the enzyme to perform diverse functions during plant development.
- Publisher
- AMER SOC PLANT BIOLOGISTS
- Keywords
- BARLEY HORDEUM-VULGARE; WALL-BOUND EXO-1,3-BETA-D-GLUCANASE; CELLULOSE-BINDING DOMAIN; CRYSTAL-STRUCTURES; CATALYTIC MECHANISM; GLYCOSIDE HYDROLASE; D-GLUCOSIDASE; PATHOGEN INTERACTIONS; SUBSITE AFFINITIES; TRICHODERMA-REESEI
- Publisher's Version
- https://doi.org/10.1105/tpc.010442
- Terms of Use/Rights Notice
- Refer to copyright notice on published article.
Creation Date: 2002-05-01 12:00:00