title: Escherichia coli heptosyltransferase I: investigation of protein dynamics of a GT-B structural enzyme.
abstract: Heptosyltransferase I (HepI), the enzyme responsible for the transfer of l-glycero-d-manno-heptose to a 3-deoxy-α-d-manno-oct-2-ulopyranosonic acid (Kdo) of the growing core region of lipopolysaccharide, is a member of the GT-B structural class of enzymes. Crystal structures have revealed open and closed conformations of apo and ligand-bound GT-B enzymes, implying that large-scale protein conformational dynamics play a role in their reaction mechanism. Here we report transient kinetic analysis of conformational changes in HepI reported by intrinsic tryptophan fluorescence and present the first real-time evidence of a GT-B enzyme undergoing a substrate binding-induced transition from an open to closed state prior to catalysis.
authors.affiliation: Department of Chemistry, Wesleyan University , Middletown, Connecticut 06459, United States.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Czyzyk
authors.forename: Shreya S
authors.initials: SS
authors.lastname: Sawant
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Ramirez-Mondragon
authors.forename: Manju M
authors.initials: MM
authors.lastname: Hingorani
authors.forename: Erika A
authors.initials: EA
authors.lastname: Taylor
mesh_terms: D003460:Crystallization; D004926:Escherichia coli / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016695:Glycosyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D011485:Protein Binding; D011487:Protein Conformation; D013379:Substrate Specificity
chemical_list: D029968:Escherichia coli Proteins; D016695:Glycosyltransferases; C086735:heptosyltransferase