An Antirepressor, SrpR, Is Involved in Transcriptional Regulation of the SrpABC Solvent Tolerance Efflux Pump of Pseudomonas putida S12
An Antirepressor, SrpR, Is Involved in Transcriptional Regulation of the SrpABC Solvent Tolerance Efflux Pump of Pseudomonas putida S12
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DOI：
10.1128/jb.00149-11
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发表时间：
2011-03
影响因子：
3.2
通讯作者：
Xu Sun;Zileena Zahir;Karlene H. Lynch;J. Dennis
中科院分区：
文献类型：
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作者：
Xu Sun;Zileena Zahir;Karlene H. Lynch;J. Dennis
摘要 有机化合物根据其插入生物膜并破坏正常膜功能的能力，对生物体表现出不同程度的毒性。许多细菌耐受有机溶剂的主要机制是通过外排泵进行能量依赖性挤出。其中一种细菌菌株恶臭假单胞菌 S12 因其对 SrpABC 抗性结瘤细胞分裂 (RND) 家族外排泵提供的有机溶剂的高耐受性而闻名。为了确定两种假定的调节蛋白（SrpR 和 SrpS，直接在 SrpABC 结构基因上游编码）如何影响 SrpABC 外排泵表达，我们进行了转录分析、β-半乳糖苷酶融合实验、电泳迁移率变化测定和下拉分析。总之，这些实验的结果表明，srpABC 操纵子的表达可以通过两种不同但互补的机制去抑制：有机溶剂直接抑制 SrpS 阻遏物，以及其抗阻遏物 SrpR 结合 SrpS。
ABSTRACT Organic compounds exhibit various levels of toxicity toward living organisms based upon their ability to insert into biological membranes and disrupt normal membrane function. The primary mechanism responsible for organic solvent tolerance in many bacteria is energy-dependent extrusion via efflux pumps. One such bacterial strain, Pseudomonas putida S12, is known for its high tolerance to organic solvents as provided through the SrpABC resistance-nodulation-cell division (RND) family efflux pump. To determine how two putative regulatory proteins (SrpR and SrpS, encoded directly upstream of the SrpABC structural genes) influence SrpABC efflux pump expression, we conducted transcriptional analysis, β-galactosidase fusion experiments, electrophoretic mobility shift assays, and pulldown analysis. Together, the results of these experiments suggest that expression of the srpABC operon can be derepressed by two distinct but complementary mechanisms: direct inhibition of the SrpS repressor by organic solvents and binding of SrpS by its antirepressor SrpR.