REGULATION OF SUGAR TRANSPORT AND METABOLISM IN LACTIC ACID AND ORAL BACTERIA

梭菌的碳水化合物发酵的研究导致发现一种新的二糖磷酸水解酶在F. mortiferum。这种独特的磷酸-α-葡萄糖苷酶（GlvA）水解许多磷酸化化合物（包括麦芽糖-6-磷酸），并且需要二价金属离子和核苷酸（NAD）来实现活性。在过去的一年中，来自枯草芽孢杆菌的相同酶已被克隆并从高表达系统中纯化（Thompson等，1998 J.Biol.Chem.273：27347）。蛋白质已经结晶。使用同步辐射，薄棒状晶体的折射率超过2.2埃，并且已经报道了初步的X射线结构（Varrot等人，1999 Acta Cryst.D55：1212）。定点诱变技术已经初步鉴定了核苷酸结合结构域的β-α-β折叠和酶活性位点的两个催化谷氨酰残基。一种相关的但立体化学上不同的磷酸-β-葡糖苷酶（CelF）也已经从大肠杆菌中鉴定、克隆和纯化。这种酶水解纤维二糖-6-磷酸，并且像芽孢杆菌酶一样，CelF还需要金属离子和NAD的活性。这些新的细菌酶被分配到家族4的糖基水解酶。- 磷酸-α-葡萄糖苷酶，枯草芽孢杆菌，CELF，大肠杆菌，葡萄糖基水解酶家族4

Studies of carbohydrate fermentation by Fusobacteria led to the discovery of a novel disaccharide phosphate hydrolase in F.mortiferum. This unique phospho-alpha-glucosidase (GlvA) hydrolyzed many phosphorylated compounds (including maltose-6- phosphate) and required divalent metal metal ion and nucleotide (NAD) for activity. In the past year, the same enzyme from Bacillus subtilis has been cloned and purified from a high expression system (Thompson et al. 1998 J. Biol. Chem.273:27347). The protein has now been crystallized. The thin rod-like crystals diffract beyond 2.2 Angstroms using synchrotron radiation, and a preliminary X-ray structure has been reported (Varrot et al. 1999 Acta Cryst. D55: 1212). Site-directed mutagenesis has allowed tentative identification of the beta-alpha-beta fold of the nucleotide-binding domain and the two catalytic glutamyl residues of the active site of the enzyme.A related, but stereochemically distinct, phospho- beta-glucosidase (CelF) has also been identified, cloned and purified from Escherichia coli.This enzyme hydrolyzes cellobiose-6-phosphate and, like the Bacillus enzyme, CelF also requires metal ion and NAD for activity. These novel bacterial enzymes are assigned to Family 4 of glycosylhydrolases. - PHOSPHO-ALPHA-GLUCOSIDASE, BACILLUS SUBTILIS, CELF, ESCHERICHIA COLI, FAMILY 4 OF GLYCOSYLHYDROLASES