Glycoside Hydrolases Family 4; GlvA- and pagL-like glycosidases.
Bacillus subtilis GlvA and Clostridium acetobutylicum pagL are 6-phospho-alpha-glucosidase, catalyzing the hydrolysis of alpha-glucopyranoside bonds to release glucose from oligosaccharides. The substrate specificities of other members of this subgroup are unknown. Some bacteria simultaneously translocate and phosphorylate disaccharides via the phosphoenolpyruvate-dependent phosphotransferase system (PEP_PTS). After translocation, these phospho-disaccharides may be hydrolyzed by the GH4 glycoside hydrolases, which include 6-phospho-beta-glucosidases, 6-phospho-alpha-glucosidases, alpha-glucosidases/alpha-glucuronidases (only from Thermotoga), and alpha-galactosidases. Members of this subfamily are part of the NAD(P)-binding Rossmann fold superfamily, which includes a wide variety of protein families including the NAD(P)-binding domains of alcohol dehydrogenases, tyrosine-dependent oxidoreductases, glyceraldehyde-3-phosphate dehydrogenases, formate/glycerate dehydrogenases, siroheme synthases, 6-phosphogluconate dehydrogenases, aminoacid dehydrogenases, repressor rex, and NAD-binding potassium channel domains, among others.