InterPro domain: IPR044112

YihQ is a sulfoquinovosidase that catalyses hydrolysis of sulfoquinovosyl diacylglycerides (SQDG) to sulfoquinovose (SQ), which is then degraded by E.coli through the SQ Embden-Meyerhof-Parnas (SQ-EMP) sulfoglycolysis pathway as a source of carbon and sulfur [ 1 ]. It also exhibits some alpha-glucosidase activity against alpha-glucosyl fluoride in vitro, although natural substrates, such as alpha-glucobioses are scarcely hydrolyzed [ 2 ]. Orthologs of YihQ that have not yet been functionally characterised are present in plants and fungi. YihQ has sequence similarity to other GH31 enzymes such as CtsZ, a 6-alpha-glucosyltransferase from Bacillus globisporus, and YicI, an alpha-xylosidase from E. coli [ 3 ].

1. YihQ is a sulfoquinovosidase that cleaves sulfoquinovosyl diacylglyceride sulfolipids. Nat. Chem. Biol. 12, 215-7
2. Overexpression and characterization of two unknown proteins, YicI and YihQ, originated from Escherichia coli. Protein Expr. Purif. 37, 170-9
3. Structure of the Sulfolobus solfataricus alpha-glucosidase: implications for domain conservation and substrate recognition in GH31. J. Mol. Biol. 358, 1106-24