The TetR-Type MfsR Protein of the Integrative and Conjugative Element (ICE) ICEclc Controls both a Putative Efflux System and Initiation of ICE Transfer
The TetR-Type MfsR Protein of the Integrative and Conjugative Element (ICE) ICEclc Controls both a Putative Efflux System and Initiation of ICE Transfer
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DOI：
10.1128/jb.02129-14
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发表时间：
2014-09
影响因子：
3.2
通讯作者：
N. Pradervand;François Delavat;S. Sulser;Ryo Miyazaki;J. R. van der Meer
中科院分区：
文献类型：
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作者：
N. Pradervand;François Delavat;S. Sulser;Ryo Miyazaki;J. R. van der Meer
摘要整合和接合元件（ICE）是广泛存在于细菌基因组中的可自我转移的DNA，通常携带有多种具有潜在适应性的辅助基因。ICE模型之一是ICEclc，这是一种最初在克氏假单胞菌B13中发现的元素，并以其倾向于为其宿主提供代谢氯儿茶酚和2-氨基苯酚的能力而闻名。在这项工作中，我们研究了MfsR的调节机制和靶点，MfsR是一种TetR型阻遏物，以前发现对ICEclc水平转移施加全局控制。通过使用ICEclc突变体和转录组分析，基因报告融合，和DNA结合试验的组合，我们发现，MfsR是一个阻遏物，它自己的表达和一个基因簇pupillary编码的主要促进超家族外排系统ICEclc（命名为mfsABC）。系统发育分析表明，mfsR最初位于紧邻的外排泵基因，但成为取代其原来的顺式靶DNA的基因插入。这导致原始双向启动子分化成两个独立的调控单元。mfsABC的缺失没有导致强表型，尽管筛选了大量的化合物和条件，我们无法定义精确的电流功能或推定的外排泵的目标。我们的数据重建了祖先mfsR-mfsABC系统的分离如何导致MfsR对ICEclc转移的全局控制。
ABSTRACT Integrative and conjugating elements (ICE) are self-transferable DNAs widely present in bacterial genomes, which often carry a variety of auxiliary genes of potential adaptive benefit. One of the model ICE is ICEclc, an element originally found in Pseudomonas knackmussii B13 and known for its propensity to provide its host with the capacity to metabolize chlorocatechols and 2-aminophenol. In this work, we studied the mechanism and target of regulation of MfsR, a TetR-type repressor previously found to exert global control on ICEclc horizontal transfer. By using a combination of ICEclc mutant and transcriptome analysis, gene reporter fusions, and DNA binding assays, we found that MfsR is a repressor of both its own expression and that of a gene cluster putatively coding for a major facilitator superfamily efflux system on ICEclc (named mfsABC). Phylogenetic analysis suggests that mfsR was originally located immediately adjacent to the efflux pump genes but became displaced from its original cis target DNA by a gene insertion. This resulted in divergence of the original bidirectional promoters into two separated individual regulatory units. Deletion of mfsABC did not result in a strong phenotype, and despite screening a large number of compounds and conditions, we were unable to define the precise current function or target of the putative efflux pump. Our data reconstruct how the separation of an ancestor mfsR-mfsABC system led to global control of ICEclc transfer by MfsR.