Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.
Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
J Bacteriol. 2018 Feb 23;200(6). doi: 10.1128/JB.00722-17. Print 2018 Mar 15.
Bacteria respond to stressful growth conditions through a conserved phenomenon of stringent response mediated by synthesis of stress alarmones ppGpp and pppGpp [referred to as (p)ppGpp]. (p)ppGpp synthesis is known to occur by ribosome-associated RelA. In addition, a dual-function protein, SpoT (with both synthetase and hydrolase activities), maintains (p)ppGpp homeostasis. The presence of (p)ppGpp is also known to contribute to antibiotic resistance in bacteria. possesses Arr, which inactivates rifampin by its ADP ribosylation. Arr has been shown to be upregulated in response to stress. However, the roles Arr might play during growth have remained unclear. We show that Arr confers growth fitness advantage to even in the absence of rifampin. Arr deficiency in resulted in deficiency of biofilm formation. Further, we show that while Arr does not interact with the wild-type ribosomes, it interacts with them when the ribosomal protein L11 (a stringent response regulator) is replaced with its homolog from The Arr interaction with ribosomes occurs even when the N-terminal 33 amino acids of its L11 protein were replaced with the corresponding sequence of L11 (L11 chimeric protein). Interestingly, Arr interaction with the ribosomes harboring L11 or L11 results in the synthesis of ppGpp Our study shows a novel role of antibiotic resistance gene in stress response., like many other bacteria, possesses an ADP-ribosyltransferase, Arr, which confers resistance to the first-line antituberculosis drug, rifampin, by its ADP ribosylation. In this report, we show that in addition to its known property of conferring resistance to rifampin, Arr confers growth fitness advantage to even when there is no rifampin in the growth medium. We then show that Arr establishes species-specific interactions with ribosomes through the N-terminal sequence of ribosomal protein L11 (a stringent response regulator) and results in ppGpp (stress alarmone) synthesis. Deficiency of Arr in results in deficiency of biofilm formation. Arr protein is physiologically important both in conferring antibiotic resistance as well as in mediating stringent response.
细菌通过由应激警报核苷酸 ppGpp 和 pppGpp [简称 (p)ppGpp] 合成介导的严格响应的保守现象来应对有压力的生长条件。据了解，(p)ppGpp 的合成是由与核糖体相关的 RelA 发生的。此外，一种双功能蛋白 SpoT（具有合成酶和水解酶活性）维持 (p)ppGpp 的动态平衡。据了解，(p)ppGpp 的存在也有助于细菌对抗生素产生耐药性。 含有 Arr，通过 ADP 核糖基化使其失活。已经表明 Arr 会被应激上调。然而，Arr 在生长过程中可能发挥的作用仍不清楚。我们表明，即使没有利福平，Arr 也能使 获得生长适应性优势。 中 Arr 的缺乏导致生物膜形成不足。此外，我们表明，虽然 Arr 与野生型 核糖体没有相互作用，但当 核糖体蛋白 L11（严格响应调节剂）被其来自 的同源物替换时，它与它们相互作用。即使其 L11 蛋白的 N 端 33 个氨基酸被 L11 的相应序列（L11 嵌合蛋白）替换，Arr 与 核糖体的相互作用也会发生。有趣的是，Arr 与含有 L11 或 L11 的 核糖体相互作用导致 ppGpp 的合成。我们的研究表明，抗生素耐药基因 在应激反应中具有新的作用。与许多其他细菌一样， 含有 ADP-核糖基转移酶 Arr，通过其 ADP 核糖基化赋予对一线抗结核药物利福平的耐药性。在本报告中，我们表明，除了已知赋予利福平耐药性的特性外，Arr 即使在生长培养基中没有利福平的情况下，也能使 获得生长适应性优势。然后我们表明，Arr 通过核糖体蛋白 L11（严格响应调节剂）的 N 端序列与核糖体建立种特异性相互作用，并导致 ppGpp（应激警报核苷酸）的合成。 中 Arr 的缺乏导致生物膜形成不足。Arr 蛋白在赋予抗生素耐药性和介导严格响应方面都是生理上重要的。
