PDF(Pubmed)
Abstract：
Since antibiotic resistance is often associated with a fitness cost, bacteria employ multi-layered regulatory mechanisms to ensure that expression of resistance factors is restricted to times of antibiotic challenge. In Bacillus subtilis, the chromosomally-encoded ABCF ATPase VmlR confers resistance to pleuromutilin, lincosamide and type A streptogramin translation inhibitors. Here we show that vmlR expression is regulated by translation attenuation and transcription attenuation mechanisms. Antibiotic-induced ribosome stalling during translation of an upstream open reading frame in the vmlR leader region prevents formation of an anti-antiterminator structure, leading to the formation of an antiterminator structure that prevents intrinsic termination. Thus, transcription in the presence of antibiotic induces vmlR expression. We also show that NusG-dependent RNA polymerase pausing in the vmlR leader prevents leaky expression in the absence of antibiotic. Furthermore, we demonstrate that induction of VmlR expression by compromised protein synthesis does not require the ability of VmlR to rescue the translational defect, as exemplified by constitutive induction of VmlR by ribosome assembly defects. Rather, the specificity of induction is determined by the antibiotic\'s ability to stall the ribosome on the regulatory open reading frame located within the vmlR leader. Finally, we demonstrate the involvement of (p)ppGpp-mediated signalling in antibiotic-induced VmlR expression.
摘要：
由于抗生素耐药性通常与健身成本有关，细菌采用多层调节机制来确保抗性因子的表达仅限于抗生素攻击的时间。在枯草芽孢杆菌中,染色体编码的ABCFATP酶VmlR赋予对截短侧耳素的抗性，lincosamide和A型链谱蛋白翻译抑制剂。在这里，我们表明vmlR表达受翻译衰减和转录衰减机制的调节。在vmlR前导区的上游开放阅读框翻译过程中，抗生素诱导的核糖体停滞可防止形成抗终止子结构，导致形成防止内在终止的抗终止子结构。因此，在抗生素存在下的转录诱导vmlR表达。我们还表明，在vmlR前导序列中暂停NusG依赖性RNA聚合酶可防止在不存在抗生素的情况下泄漏表达。此外，我们证明，通过受损的蛋白质合成诱导VmlR表达不需要VmlR挽救翻译缺陷的能力，例如通过核糖体组装缺陷对VmlR的本构诱导。相反，诱导的特异性取决于抗生素在vmlR前导序列内的调节开放阅读框上阻止核糖体的能力。最后,我们证明了（p）ppGpp介导的信号参与抗生素诱导的VmlR表达。
