Chan Albert H, Yi Sung Wook, Weiner Ethan M, Amer Brendan R, Sue Christopher K, Wereszczynski Jeff, Dillen Carly A, Senese Silvia, Torres Jorge Z, McCammon J Andrew, Miller Lloyd S, Jung Michael E, Clubb Robert T
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA.
UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, Los Angeles, CA, USA.
Chem Biol Drug Des. 2017 Sep;90(3):327-344. doi: 10.1111/cbdd.12962. Epub 2017 Mar 6.
Staphylococcus aureus is a leading cause of hospital-acquired infections in the USA and is a major health concern as methicillin-resistant S. aureus and other antibiotic-resistant strains are common. Compounds that inhibit the S. aureus sortase (SrtA) cysteine transpeptidase may function as potent anti-infective agents as this enzyme attaches virulence factors to the bacterial cell wall. While a variety of SrtA inhibitors have been discovered, the vast majority of these small molecules have not been optimized using structure-based approaches. Here we have used NMR spectroscopy to determine the molecular basis through which pyridazinone-based small molecules inhibit SrtA. These inhibitors covalently modify the active cysteine thiol and partially mimic the natural substrate of SrtA by inducing the closure of an active site loop. Computational and synthetic chemistry methods led to second-generation analogues that are ~70-fold more potent than the lead molecule. These optimized molecules exhibit broad-spectrum activity against other types of class A sortases, have reduced cytotoxicity, and impair SrtA-mediated protein display on S. aureus cell surface. Our work shows that pyridazinone analogues are attractive candidates for further development into anti-infective agents, and highlights the utility of employing NMR spectroscopy and solubility-optimized small molecules in structure-based drug discovery.
金黄色葡萄球菌是美国医院获得性感染的主要原因，由于耐甲氧西林金黄色葡萄球菌和其他耐药菌株很常见，它成为一个主要的健康问题。抑制金黄色葡萄球菌分选酶（SrtA）半胱氨酸转肽酶的化合物可能作为有效的抗感染剂发挥作用，因为这种酶将毒力因子附着于细菌细胞壁。虽然已经发现了多种SrtA抑制剂，但绝大多数这些小分子尚未通过基于结构的方法进行优化。在这里，我们使用核磁共振光谱来确定基于哒嗪酮的小分子抑制SrtA的分子基础。这些抑制剂共价修饰活性半胱氨酸硫醇，并通过诱导活性位点环的闭合部分模拟SrtA的天然底物。计算和合成化学方法产生了第二代类似物，其效力比先导分子高约70倍。这些优化的分子对其他类型的A类分选酶具有广谱活性，降低了细胞毒性，并损害了SrtA介导的蛋白质在金黄色葡萄球菌细胞表面的展示。我们的工作表明，哒嗪酮类似物是进一步开发成抗感染剂的有吸引力的候选物，并突出了在基于结构的药物发现中使用核磁共振光谱和溶解度优化的小分子的实用性。
