Craney Arryn, Romesberg Floyd E
Department of Chemistry, The Scripps Research Institute, La Jolla, California, USA.
Department of Chemistry, The Scripps Research Institute, La Jolla, California, USA
Antimicrob Agents Chemother. 2015;59(6):3066-74. doi: 10.1128/AAC.04597-14. Epub 2015 Mar 9.
Antibiotic-resistant bacteria are a significant public health concern and motivate efforts to develop new classes of antibiotics. One such class of antibiotics is the arylomycins, which target type I signal peptidase (SPase), the enzyme responsible for the release of secreted proteins from their N-terminal leader sequences. Despite the essentiality, conservation, and relative accessibility of SPase, the activity of the arylomycins is limited against some bacteria, including the important human pathogen Staphylococcus aureus. To understand the origins of the limited activity against S. aureus, we characterized the susceptibility of a panel of strains to two arylomycin derivatives, arylomycin A-C16 and its more potent analog arylomycin M131. We observed a wide range of susceptibilities to the two arylomycins and found that resistant strains were sensitized by cotreatment with tunicamycin, which inhibits the first step of wall teichoic acid synthesis. To further understand how S. aureus responds to the arylomycins, we profiled the transcriptional response of S. aureus NCTC 8325 to growth-inhibitory concentrations of arylomycin M131 and found that it upregulates the cell wall stress stimulon (CWSS) and an operon consisting of a putative transcriptional regulator and three hypothetical proteins. Interestingly, we found that mutations in the putative transcriptional regulator are correlated with resistance, and selection for resistance ex vivo demonstrated that mutations in this gene are sufficient for resistance. The results begin to elucidate how S. aureus copes with secretion stress and how it evolves resistance to the inhibition of SPase.
抗生素耐药细菌是一个重大的公共卫生问题，这促使人们努力开发新型抗生素。芳基霉素就是这样一类抗生素，它作用于I型信号肽酶（SPase），该酶负责从分泌蛋白的N端前导序列中释放出这些蛋白。尽管SPase具有重要性、保守性且相对易于作用，但芳基霉素对某些细菌的活性有限，包括重要的人类病原体金黄色葡萄球菌。为了了解对金黄色葡萄球菌活性有限的原因，我们对一组菌株对两种芳基霉素衍生物（芳基霉素A - C16及其更强效的类似物芳基霉素M131）的敏感性进行了表征。我们观察到这些菌株对这两种芳基霉素的敏感性差异很大，并且发现耐药菌株在用衣霉素共同处理后变得敏感，衣霉素可抑制壁磷壁酸合成的第一步。为了进一步了解金黄色葡萄球菌对芳基霉素的反应，我们分析了金黄色葡萄球菌NCTC 8325对抑制生长浓度的芳基霉素M131的转录反应，发现它上调了细胞壁应激刺激因子（CWSS）以及一个由一个假定的转录调节因子和三个假定蛋白组成的操纵子。有趣的是，我们发现该假定转录调节因子中的突变与耐药性相关，并且在体外选择耐药性表明该基因中的突变足以导致耐药。这些结果开始阐明金黄色葡萄球菌如何应对分泌应激以及它如何进化出对SPase抑制的耐药性。
