title: Crystal structure of the DNA modifying enzyme beta-glucosyltransferase in the presence and absence of the substrate uridine diphosphoglucose.
abstract: Bacteriophage T4 beta-glucosyltransferase (EC 2.4.1.27) catalyses the transfer of glucose from uridine diphosphoglucose to hydroxymethyl groups of modified cytosine bases in T4 duplex DNA forming beta-glycosidic linkages. The enzyme forms part of a phage DNA protection system. We have solved and refined the crystal structure of recombinant beta-glucosyltransferase to 2.2 A resolution in the presence and absence of the substrate, uridine diphosphoglucose. The structure comprises two domains of similar topology, each reminiscent of a nucleotide binding fold. The two domains are separated by a central cleft which generates a concave surface along one side of the molecule. The substrate-bound complex reveals only clear electron density for the uridine diphosphate portion of the substrate. The UDPG is bound in a pocket at the bottom of the cleft between the two domains and makes extensive hydrogen bonding contacts with residues of the C-terminal domain only. The domains undergo a rigid body conformational change causing the structure to adopt a more closed conformation upon ligand binding. The movement of the domains is facilitated by a hinge region between residues 166 and 172. Electrostatic surface potential calculations reveal a large positive potential along the concave surface of the structure, suggesting a possible site for duplex DNA interaction.
authors.affiliation: Protein Structure Laboratory, Imperial Cancer Research Fund, London.
authors.forename: A
authors.initials: A
authors.lastname: Vrielink
authors.forename: W
authors.initials: W
authors.lastname: Rüger
authors.forename: H P
authors.initials: HP
authors.lastname: Driessen
authors.forename: P S
authors.initials: PS
authors.lastname: Freemont
mesh_terms: D017122:Bacteriophage T4 / Q000201:enzymology; D001665:Binding Sites; D002384:Catalysis; D003196:Computer Graphics; D003460:Crystallization; D018360:Crystallography, X-Ray; D004247:DNA / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D005964:Glucosyltransferases / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D015394:Molecular Structure; D011487:Protein Conformation; D014532:Uridine Diphosphate Glucose / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004247:DNA; D005964:Glucosyltransferases; C026585:DNA beta-glucosyltransferase; D005947:Glucose; D014532:Uridine Diphosphate Glucose