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The ColR–ColS two‐component signal transduction system is involved in regulation of Tn 4652 transposition in Pseudomonas putida under starvation conditions
Author(s) -
Hõrak Rita,
Ilves Heili,
Pruunsild Priit,
Kuljus Martin,
Kivisaar Maia
Publication year - 2004
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2004.04311.x
Subject(s) - biology , response regulator , histidine kinase , pseudomonas putida , mutant , signal transduction , transposable element , transposon mutagenesis , transposition (logic) , microbiology and biotechnology , transduction (biophysics) , genetics , mutagenesis , biochemistry , bacteria , gene , linguistics , philosophy
Summary Bacteria use two‐component signal transduction pathways to sense both extracellular and intracellular environment and to coordinate cellular events according to changing conditions. Adaptation can be either physiological or genetical. Here, we present evidence that a genome reorganization process such as transposition can be controlled by certain environmental cues sensed by a two‐component signal transduction system. We demonstrate that transposition‐dependent accumulation of phenol‐utilizing mutants is severely decreased in Pseudomonas putida defective in a two‐component system colRS . Translocation of Tn 4652 is decreased both in colR ‐ and colS ‐defective strains, indicating that signal transduction from a histidine kinase ColS to a response regulator ColR is necessary for the activation of Tn 4652 in bacteria starving on phenol. However, overexpression of ColR in a colS ‐defective strain restores Tn 4652 transposition, suggesting that absence of the signal from ColS can be compensated by an elevated amount of ColR. In vitro analysis of purified ColR and ColS proteins evidenced that they constitute a functional phosphorelay. Site‐directed mutagenesis revealed that a conserved H221 can be the phosphoryl‐accepting residue in ColS and that aspartate residues D8 and D51 of ColR are necessary for the phosphotransfer from ColS to ColR. To our knowledge, Tn 4652 is the first bacterial transposon regulated by a two‐component system. This finding indicates that transpositional activity can respond to signals sensed and processed by the host.