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.

中文翻译：

---

A类β-内酰胺酶TEM-171的晶体结构及其与他唑巴坦的复合物

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，展示了天然 β-内酰胺酶 TEM-171 的新晶体结构和两种与广泛使用的抑制剂他唑巴坦的复合物，以及来自紫外光谱和荧光猝灭的补充数据。晶体不对称单元中的六个化学上相同的β-内酰胺酶分子显示出不同程度的无序。他唑巴坦中间体在反式中与催化 Ser70 共价结合-烯胺配置。虽然他唑巴坦在第一个复合物中的构象类似于已发表的 β-内酰胺酶-他唑巴坦结构，但在第二个复合物中，这是在将天然晶体长时间浸泡在抑制剂溶液中后获得的，观察到一种新的和以前未报道的他唑巴坦构象。提出这两种复合物对应于酰基酶中间体脱酰路径的不同阶段。该结果为合理设计新型β-内酰胺酶抑制剂提供了新的结构基础。