Caselli Emilia, Fini Francesco, Introvigne Maria Luisa, Stucchi Mattia, Taracila Magdalena A, Fish Erin R, Smolen Kali A, Rather Philip N, Powers Rachel A, Wallar Bradley J, Bonomo Robert A, Prati Fabio
Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 103, Modena 41125, Italy.
Clinical and Experimental Medicine PhD Program, University of Modena and Reggio Emilia, Modena 41125, Italy.
ACS Infect Dis. 2020 Jul 10;6(7):1965-1975. doi: 10.1021/acsinfecdis.0c00254. Epub 2020 Jun 24.
Boronic acid transition state inhibitors (BATSIs) are known reversible covalent inhibitors of serine β-lactamases. The selectivity and high potency of specific BATSIs bearing an amide side chain mimicking the β-lactam's amide side chain are an established and recognized synthetic strategy. Herein, we describe a new class of BATSIs where the amide group is replaced by a bioisostere triazole; these compounds were designed as molecular probes. To this end, a library of 26 α-triazolylmethaneboronic acids was synthesized and tested against the clinically concerning -derived cephalosporinase, ADC-7. In steady state analyses, these compounds demonstrated values ranging from 90 nM to 38 μM (±10%). Five compounds were crystallized in complex with ADC-7 β-lactamase, and all the crystal structures reveal the triazole is in the putative amide binding site, thus confirming the triazole-amide bioisosterism. The easy synthetic access of these new inhibitors as prototype scaffolds allows the insertion of a wide range of chemical groups able to explore the enzyme binding site and provides insights on the importance of specific residues in recognition and catalysis. The best inhibitor identified, compound ( 90 nM), places a tolyl group near Arg340, making favorable cation-π interactions. Notably, the structure of does not resemble the natural substrate of the β-lactamase yet displays a pronounced inhibition activity, in addition to lowering the minimum inhibitory concentration (MIC) of ceftazidime against three bacterial strains expressing class C β-lactamases. In summary, these observations validate the α-triazolylboronic acids as a promising template for further inhibitor design.
硼酸过渡态抑制剂（BATSIs）是已知的丝氨酸β-内酰胺酶可逆共价抑制剂。带有模拟β-内酰胺酰胺侧链的酰胺侧链的特定BATSIs的选择性和高效性是一种既定且公认的合成策略。在此，我们描述了一类新型的BATSIs，其中酰胺基团被生物电子等排体三唑取代；这些化合物被设计为分子探针。为此，合成了一个包含26种α-三唑基甲烷硼酸的文库，并针对临床上关注的源自头孢菌素酶的ADC-7进行了测试。在稳态分析中，这些化合物的 值范围为90 nM至38 μM（±10%）。五种化合物与ADC-7β-内酰胺酶形成复合物结晶，所有晶体结构均表明三唑位于假定的酰胺结合位点，从而证实了三唑 - 酰胺生物电子等排性。这些新型抑制剂作为原型支架易于合成，能够插入多种化学基团以探索酶结合位点，并提供了关于特定残基在识别和催化中的重要性的见解。鉴定出的最佳抑制剂化合物 （90 nM）在Arg340附近放置了一个甲苯基，形成了有利的阳离子 - π相互作用。值得注意的是， 的结构与β-内酰胺酶的天然底物不同，但除了降低头孢他啶对三种表达C类β-内酰胺酶的细菌菌株的最低抑菌浓度（MIC）外，还表现出显著的抑制活性。总之，这些观察结果验证了α-三唑基硼酸作为进一步抑制剂设计的有前途的模板。
