Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
PLoS Pathog. 2011 Feb 10;7(2):e1001287. doi: 10.1371/journal.ppat.1001287.
Methicillin-resistant Staphylococcus aureus is estimated to cause more U.S. deaths annually than HIV/AIDS. The emergence of hypervirulent and multidrug-resistant strains has further amplified public health concern and accentuated the need for new classes of antibiotics. RNA degradation is a required cellular process that could be exploited for novel antimicrobial drug development. However, such discovery efforts have been hindered because components of the Gram-positive RNA turnover machinery are incompletely defined. In the current study we found that the essential S. aureus protein, RnpA, catalyzes rRNA and mRNA digestion in vitro. Exploiting this activity, high through-put and secondary screening assays identified a small molecule inhibitor of RnpA-mediated in vitro RNA degradation. This agent was shown to limit cellular mRNA degradation and exhibited antimicrobial activity against predominant methicillin-resistant S. aureus (MRSA) lineages circulating throughout the U.S., vancomycin intermediate susceptible S. aureus (VISA), vancomycin resistant S. aureus (VRSA) and other Gram-positive bacterial pathogens with high RnpA amino acid conservation. We also found that this RnpA-inhibitor ameliorates disease in a systemic mouse infection model and has antimicrobial activity against biofilm-associated S. aureus. Taken together, these findings indicate that RnpA, either alone, as a component of the RNase P holoenzyme, and/or as a member of a more elaborate complex, may play a role in S. aureus RNA degradation and provide proof of principle for RNA catabolism-based antimicrobial therapy.
耐甲氧西林金黄色葡萄球菌估计每年导致的美国死亡人数超过艾滋病毒/艾滋病。高毒力和多药耐药菌株的出现进一步加剧了公众健康的担忧，并强调了需要新型抗生素。RNA 降解是一种必需的细胞过程，可以被开发用于新型抗菌药物的研发。然而，由于革兰氏阳性 RNA 周转机制的成分不完全确定，此类发现工作受到了阻碍。在本研究中，我们发现必需的金黄色葡萄球菌蛋白 RnpA 在体外催化 rRNA 和 mRNA 的消化。利用这种活性，高通量和二次筛选测定法鉴定出一种 RnpA 介导的体外 RNA 降解的小分子抑制剂。该试剂被证明可限制细胞 mRNA 的降解，并对在美国流行的主要耐甲氧西林金黄色葡萄球菌（MRSA）谱系、中间耐万古霉素金黄色葡萄球菌（VISA）、耐万古霉素金黄色葡萄球菌（VRSA）和其他具有高 RnpA 氨基酸保守性的革兰氏阳性细菌病原体表现出抗菌活性。我们还发现，这种 RnpA 抑制剂可改善全身性小鼠感染模型中的疾病，并对生物膜相关的金黄色葡萄球菌具有抗菌活性。总之，这些发现表明 RnpA 无论是单独作为 RNase P 全酶的一部分，还是作为更复杂的复合物的一部分，都可能在金黄色葡萄球菌的 RNA 降解中发挥作用，并为基于 RNA 分解代谢的抗菌治疗提供了原理证明。
