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Publication Abstract from PubMed

Ruminant animals rely on the activities of beta-glucosidases from residential microbes to convert feed fibers into glucose for further metabolic uses. In this report, we determined the structures of Br2, which is a glycoside hydrolase family 1 beta-glucosidase from the bovine rumen metagenome. Br2 folds into a classical (beta/alpha)(8)-TIM barrel domain but displays unique structural features at loop beta5-->alpha5 and alpha-helix 5, resulting in different positive subsites from those of other GH1 enzymes. Br2 exhibited the highest specificity toward laminaritriose, suggesting its involvement in beta-glucan hydrolysis in digested feed. We then substituted the residues at subsites +1 and + 2 of Br2 with those of Halothermothrix orenii beta-glucosidase. The C170E and C221T mutations provided favorable interactions with glucooligosaccharide substrates at subsite +2, while the A219N mutation probably improved the substrate preference for cellobiose and gentiobiose relative to laminaribiose at subsite +1. The N407Y mutation increased the affinity toward cellooligosaccharides. These results give further insights into the molecular determinants responsible for substrate specificity in GH1 beta-glucosidases and may provide a basis for future enzyme engineering applications.

Structural and mutational analysis of glycoside hydrolase family 1 Br2 beta-glucosidase derived from bovine rumen metagenome.,Kaenying W, Tagami T, Suwan E, Pitsanuwong C, Chomngam S, Okuyama M, Kongsaeree P, Kimura A, Kongsaeree PT Heliyon. 2023 Nov 7;9(11):e21923. doi: 10.1016/j.heliyon.2023.e21923. eCollection , 2023 Nov. PMID:38034805^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.