UDP glucose-DNA beta-glucosyltransferase
uridine diphosphoglucose-deoxyribonucleate beta-glucosyltransferase
alpha-glucosyl-5-hydroxymethylcytosine in DNA
Crystal structure of the DNA modifying enzyme beta-glucosyltransferase in the presence and absence of the substrate uridine diphosphoglucose.
T4 phage beta-glucosyltransferase: substrate binding and proposed catalytic mechanism.
High resolution crystal structures of T4 phage beta-glucosyltransferase: induced fit and effect of substrate and metal binding.
A base-flipping mechanism for the T4 phage beta-glucosyltransferase and identification of a transition-state analog.
This enzyme belongs to glycosyltransferase family-63 (GT63 family), with GT-B fold. Accoriding to the paper [4], the catalytic mechanism of this enzyme has been proposed as follows: (1) Asp100 acts as a general base, which abstracts a proton from the acceptor group, hydroxymethyl group, of the 5-HMC base. (2) This activated acceptor then makes a nucleophilic attack on the C1 atom of glucose in UDP-glucose. (3) Glucose transfer proceeds via an oxocarbonium ion in its transition state and an inversion of configuration, resulting in the beta-glucosidic linkage. Moreover, the paper [4] suggested that the geometry of the active site is appropriate for an SN2 direct displacement mechanism. As for a role of magnesium, although magnesium is necessary for its full activity, there is some controversy, according to the paper [2]. This cationic ion might stablize the transition state, or activate the acceptor group of the substrate, UDP-glucose, together with Asp100. However, according to the crystal structure of this enzyme (PDB 1ixy), the magnesium ion seems to be far away from the site, although it is close to the beta-phosphate of UDP. Thus, it might stabilize the leaving group (donor group).