Liu Xue, Li Jing-Wen, Feng Zhixing, Luo Youfu, Veening Jan-Willem, Zhang Jing-Ren
Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China.
Department of Genetics and Genomic Sciences, Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
J Bacteriol. 2017 Jun 27;199(14). doi: 10.1128/JB.00054-17. Print 2017 Jul 15.
Reversible or phenotypic tolerance to antibiotics within microbial populations has been implicated in treatment failure of chronic infections and development of persister cells. However, the molecular mechanisms regulating phenotypic drug tolerance are largely unknown. In this study, we identified a four-gene operon in that contributes to henotypic olerance to ancomycin (). RNA sequencing, quantiative reverse transcriptase PCR, and transcriptional luciferase reporter experiments revealed that transcription of the operon (consisting of , , , and ) is induced by exposure to vancomycin. Further investigation showed that transcription of the operon is repressed by PtvR, a PadR family repressor. Transcriptional induction of the operon by vancomycin was achieved by transcriptional derepression of this locus, which was mediated by PtvR. Importantly, fully derepressing by deleting or overexpressing the operon with an exogenous promoter significantly enhanced vancomycin tolerance. Gene deletion analysis revealed that PtvA, PtvB, and PtvC are all required for the PtvR-regulated phenotypic tolerance to vancomycin. Finally, the results of an electrophoretic mobility shift assay with recombinant PtvR showed that PtvR represses the transcription of the operon by binding to two palindromic sequences within the promoter. Together, the locus represents an inducible system in in response to stressful conditions, including those caused by antibiotics. Reversible or phenotypic tolerance to antibiotics within microbial populations is associated with treatment failure of bacterial diseases, but the underlying mechanisms regulating phenotypic drug tolerance remain obscure. This study reports our finding of a multigene locus that contributes to inducible tolerance to vancomycin in , an important opportunistic human pathogen. The vancomycin tolerance phenotype depends on the PtvR transcriptional repressor and three predicted membrane-associated proteins encoded by the locus. This represents the first example of a gene locus in that is responsible for antibiotic tolerance and has important implications for further understanding bacterial responses and phenotypic tolerance to antibiotic treatment in this and other pathogens.
微生物群体中对抗生素的可逆性或表型耐受性与慢性感染的治疗失败及持留菌细胞的形成有关。然而，调节表型药物耐受性的分子机制在很大程度上尚不清楚。在本研究中，我们在[具体微生物名称]中鉴定出一个四基因操纵子，它有助于对万古霉素产生表型耐受性。RNA测序、定量逆转录PCR和转录荧光素酶报告实验表明，该操纵子（由[基因名称1]、[基因名称2]、[基因名称3]和[基因名称4]组成）的转录是由万古霉素诱导的。进一步研究表明，该操纵子的转录受到PadR家族阻遏物PtvR的抑制。万古霉素对该操纵子的转录诱导是通过该位点的转录去抑制实现的，这是由PtvR介导的。重要的是，通过删除[基因名称]或用外源启动子过表达该操纵子来完全去抑制[操纵子名称]，可显著增强对万古霉素的耐受性。基因缺失分析表明，PtvA、PtvB和PtvC都是PtvR调节的对万古霉素表型耐受性所必需的。最后，用重组PtvR进行的电泳迁移率变动分析结果表明，PtvR通过结合该操纵子启动子内的两个回文序列来抑制其转录。总之，该位点代表了[具体微生物名称]中一种响应应激条件（包括由抗生素引起的应激条件）的诱导系统。微生物群体中对抗生素的可逆性或表型耐受性与细菌性疾病的治疗失败有关，但调节表型药物耐受性的潜在机制仍不清楚。本研究报告了我们在[具体微生物名称]（一种重要的人类机会致病菌）中发现的一个多基因位点，它有助于对万古霉素产生诱导耐受性。万古霉素耐受性表型取决于PtvR转录阻遏物和该位点编码的三种预测的膜相关蛋白。这代表了[具体微生物名称]中第一个负责抗生素耐受性的基因位点实例，对进一步理解该病原体及其他病原体对抗生素治疗的反应和表型耐受性具有重要意义。
