Zhang Yue-Juan, Liu Xiao-Long, Wang Wen-Ming, Chen Cheng, Zhao Mu-Han, Yang Ke-Wu
Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Chemical Biology Innovation Laboratory, College of Chemistry and Materials Science, Northwest University.
Chem Pharm Bull (Tokyo). 2019;67(2):135-142. doi: 10.1248/cpb.c18-00717.
Superbug infection caused by metallo-β-lactamases (MβLs) is a global public health threat. Previous studies reported that the thioesters specifically inhibited the B3 subclass MβL L1. In this work, nine amino acid thioesters 1-9 were synthesized, the activity evaluation revealed that all of these molecules exhibited broad-spectrum inhibitory efficacy against ImiS, IMP-1, NDM-1, and L1, with IC values range of 0.02-54.9 µM (except 5 and 7 on NDM-1), and 1 was found to be the best inhibitor with IC range of 0.02-16.63 µM. Minimal inhibitory concentration (MIC) assays showed that thioesters 1, 5 and 9 restored 2-32-fold antibacterial activity of cefazolin and/or imipenem against both Escherichia coli BL21 and DH10B strain expressing ImiS, L1, IMP-1 and NDM-1 (except 5 on NDM-1), and also, thioester 1 increased 2-4-fold antimicrobial activity of cefazolin on two clinical strains Pseudomonas aeruginosa and Klebsiella pneumoniae producing NDM-1. Stability evaluation indicated that thioester 1 was partially hydrolysed by MβLs to be converted into the mercaptoacetic acid, revealing that the thioester and its hydrolysate mercaptoacetic acid jointly inhibit MβLs. Isothermal titration calorimetry (ITC) monitoring showed that thioester 1 exhibited dose-dependent inhibition on four MβLs tested, and the binding of 1/L1 showed mainly enthalpy driven, while 1/NDM-1 was found to be more entropy driven. Docking studies suggested that 1 bound to Zn(II) ion(s) preferentially via its carboxylate group, while other moieties interacted mostly with the conserved active site residues.
由金属β-内酰胺酶（MβLs）引起的超级细菌感染是全球公共卫生威胁。先前的研究报道硫酯可特异性抑制B3亚类MβL L1。在本研究中，合成了九种氨基酸硫酯1-9，活性评估表明所有这些分子对ImiS、IMP-1、NDM-1和L1均表现出广谱抑制效果，IC值范围为0.02-54.9 μM（NDM-1上的5和7除外），且发现1是最佳抑制剂，IC范围为0.02-16.63 μM。最低抑菌浓度（MIC）测定表明，硫酯1、5和9恢复了头孢唑林和/或亚胺培南对表达ImiS、L1、IMP-1和NDM-1的大肠杆菌BL21和DH10B菌株的2-32倍抗菌活性（NDM-1上的5除外），此外，硫酯1使头孢唑林对两株产生NDM-1的临床菌株铜绿假单胞菌和肺炎克雷伯菌的抗菌活性提高了2-4倍。稳定性评估表明硫酯1被MβLs部分水解转化为巯基乙酸，表明硫酯及其水解产物巯基乙酸共同抑制MβLs。等温滴定量热法（ITC）监测表明硫酯1对所测试的四种MβLs表现出剂量依赖性抑制，且1/L1的结合主要由焓驱动，而1/NDM-1则更多地由熵驱动。对接研究表明1优先通过其羧基与Zn(II)离子结合，而其他部分主要与保守的活性位点残基相互作用。
