title: Structure of the covalent adduct formed between Mycobacterium tuberculosis beta-lactamase and clavulanate.
abstract: The intrinsic resistance of Mycobacterium tuberculosis to the beta-lactam class of antibiotics arises from a chromosomally encoded, extended spectrum, class A beta-lactamase, BlaC. Herein, we report the X-ray crystallographic structure of BlaC inhibited with clavulanate at a resolution of 1.7 A with an R-factor value of 0.180 and R-free value of 0.212 for the m/ z +154 clavulanate-derived fragment observed in the active site. Structural evidence reveals the presence of hydrogen bonds to the C1 carbonyl along with a coplanar arrangement of C1, C2, C3, and N4, which favors enolization to generate a trans-alpha,beta-eneamine, stabilizing the +154 adduct from hydrolysis. The irreversible inhibition of BlaC suggests that treatment of M. tuberculosis with a combination of a beta-lactam antibiotic and clavulanate may lead to rapid bactericidal activity.
authors.affiliation: Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park AVenue, Bronx, New York 10461, USA.
authors.forename: Lee W
authors.initials: LW
authors.lastname: Tremblay
authors.forename: Jean-Emmanuel
authors.initials: JE
authors.lastname: Hugonnet
authors.forename: John S
authors.initials: JS
authors.lastname: Blanchard
mesh_terms: D019818:Clavulanic Acid / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; D001618:beta-Lactamases