Tremblay Lee W, Hugonnet Jean-Emmanuel, Blanchard John S
Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park AVenue, Bronx, New York 10461, USA.
Biochemistry. 2008 May 13;47(19):5312-6. doi: 10.1021/bi8001055. Epub 2008 Apr 19.
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.
结核分枝杆菌对β-内酰胺类抗生素的固有耐药性源于一种染色体编码的、广谱的A类β-内酰胺酶BlaC。在此，我们报告了克拉维酸抑制的BlaC的X射线晶体结构，分辨率为1.7 Å，活性位点中观察到的m/z +154克拉维酸衍生片段的R因子值为0.180，R自由值为0.212。结构证据揭示了与C1羰基存在氢键，以及C1、C2、C3和N4的共面排列，这有利于烯醇化以生成反式α,β-烯胺，从而稳定水解产生的+154加合物。BlaC的不可逆抑制表明，用β-内酰胺抗生素和克拉维酸联合治疗结核分枝杆菌可能会导致快速杀菌活性。
