Chemistry Department, M. V. Lomonosov Moscow State University, Moscow 119991, Russian Federation.
Institute of Mathematical Problems of Biology, RAS, Branch of Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences, Pushchino 142290, Russian Federation.
Acta Crystallogr D Struct Biol. 2022 Jul 1;78(Pt 7):825-834. doi: 10.1107/S2059798322004879. Epub 2022 Jun 7.
The resistance of bacteria to β-lactam antibiotics is primarily caused by the production of β-lactamases. Here, novel crystal structures of the native β-lactamase TEM-171 and two complexes with the widely used inhibitor tazobactam are presented, alongside complementary data from UV spectroscopy and fluorescence quenching. The six chemically identical β-lactamase molecules in the crystallographic asymmetric unit displayed different degrees of disorder. The tazobactam intermediate was covalently bound to the catalytic Ser70 in the trans-enamine configuration. While the conformation of tazobactam in the first complex resembled that in published β-lactamase-tazobactam structures, in the second complex, which was obtained after longer soaking of the native crystals in the inhibitor solution, a new and previously unreported tazobactam conformation was observed. It is proposed that the two complexes correspond to different stages along the deacylation path of the acyl-enzyme intermediate. The results provide a novel structural basis for the rational design of new β-lactamase inhibitors.
细菌对β-内酰胺类抗生素的耐药性主要是由β-内酰胺酶的产生引起的。在这里，我们呈现了新型的天然β-内酰胺酶 TEM-171 的晶体结构，以及与广泛使用的抑制剂他唑巴坦的两个复合物的结构，同时还提供了来自紫外光谱和荧光猝灭的补充数据。在晶体学不对称单元中的六个化学上相同的β-内酰胺酶分子表现出不同程度的无序性。他唑巴坦的中间体以反式烯胺的形式与催化 Ser70 共价结合。虽然第一个复合物中他唑巴坦的构象与已发表的β-内酰胺酶-他唑巴坦结构相似，但在第二个复合物中，在更长时间地将天然晶体浸泡在抑制剂溶液中后获得，观察到了一种新的、以前未报道过的他唑巴坦构象。我们提出，这两个复合物对应于酰基-酶中间体的脱酰基路径的不同阶段。这些结果为新的β-内酰胺酶抑制剂的合理设计提供了新的结构基础。
