title: A novel inhibitor that suspends the induced fit mechanism of UDP-N-acetylglucosamine enolpyruvyl transferase (MurA).
abstract: MurA (UDP-N-acetylglucosamine enolpyruvyl transferase, EC 2.5.1.7) catalyzes the first committed step in the synthesis of the bacterial cell wall. It is the target of the naturally occurring, broad-spectrum antibiotic fosfomycin. Fosfomycin, an epoxide, is a relatively poor drug because an ever-increasing number of bacteria have developed resistance to fosfomycin. Thus, there is a critical need for the development of novel drugs that target MurA by a different molecular mode of action. We have identified a new scaffold of potent MurA inhibitors, derivatives of 5-sulfonoxy-anthranilic acid, using high-throughput screening. T6361 and T6362 are competitive inhibitors of MurA with respect to the first substrate, UDP-N-acetylglucosamine (UNAG), with a K(i) of 16 microM. The crystal structure of the MurA.T6361 complex at 2.6 angstrom resolution, together with fluorescence data, revealed that the inhibitor targets a loop, Pro112 to Pro121, that is crucial for the structural changes of the enzyme during catalysis. Thus, this new class of MurA inhibitors is not active site-directed but instead obstructs the transition from the open (unliganded) to the closed (UNAG-liganded) enzyme form. The results provide evidence for the existence of a MurA.UNAG collision complex that may be specifically targeted by small molecules different from ground-state analogs of the enzymatic reaction.
authors.affiliation: Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Susanne
authors.initials: S
authors.lastname: Eschenburg
authors.forename: Melanie A
authors.initials: MA
authors.lastname: Priestman
authors.forename: Farid A
authors.initials: FA
authors.lastname: Abdul-Latif
authors.forename: Carole
authors.initials: C
authors.lastname: Delachaume
authors.forename: Florence
authors.initials: F
authors.lastname: Fassy
authors.forename: Ernst
authors.initials: E
authors.lastname: Schönbrunn
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000378:metabolism; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D004352:Drug Resistance, Microbial; D016972:Enterobacter cloacae / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism*; D005578:Fosfomycin / Q000378:metabolism; D046911:Macromolecular Substances; D008958:Models, Molecular; D015394:Molecular Structure; D009282:Naphthalenesulfonates / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D046911:Macromolecular Substances; D009282:Naphthalenesulfonates; C501313:T 6361; D005578:Fosfomycin; D001224:Aspartic Acid; D019883:Alkyl and Aryl Transferases; C022566:UDP-N-acetylglucosamine 1-carboxyvinyltransferase