A broad-spectrum α-glucosidase of glycoside hydrolase family 13 fromMarinovumsp., a member of theRoseobacterclade

Abstract

AbstractGlycoside hydrolases (GHs) are a diverse group of enzymes that catalyze the hydrolysis of glycosidic bonds. The Carbohydrate-Active enZymes (CAZy) classification organizes GHs into families based on sequence data and function, with fewer than 1% of the predicted proteins characterized biochemically. Consideration of genomic context can provide clues to infer possible enzyme activities for proteins of unknown function. We used the MultiGeneBLAST tool to discover a gene cluster inMarinovumsp., a member of the marineRoseobacterclade, that encodes homologues of enzymes belonging to the sulfoquinovose monooxygenase pathway for sulfosugar catabolism. This cluster lacks a gene encoding a classical family GH31 sulfoquinovosidase candidate, but which instead includes an uncharacterized family GH13 protein (MsGH13) that we hypothesized could be a non-classical sulfoquinovosidase. Surprisingly, recombinantMsGH13 lacks sulfoquinovosidase activity and is a broad spectrum α-glucosidase that is active on a diverse array of α-linked disaccharides, including: maltose, sucrose, nigerose, trehalose, isomaltose, and kojibiose. Using AlphaFold, a 3D model for theMsGH13 enzyme was constructed that predicted its active site shared close similarity with an α-glucosidase fromHalomonassp. H11 of the same GH13 subfamily that shows narrower substrate specificity.