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Conserved two‐component H ik34‐ R re1 module directly activates heat‐stress inducible transcription of major chaperone and other genes in S ynechococcus elongatus PCC 7942
Author(s) -
Kobayashi Ikki,
Watanabe Satoru,
Kanesaki Yu,
Shimada Tomohiro,
Yoshikawa Hirofumi,
Tanaka Kan
Publication year - 2017
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/mmi.13624
Subject(s) - biology , response regulator , histidine kinase , gene , transcription factor , heat shock protein , chromatin immunoprecipitation , chaperone (clinical) , promoter , two component regulatory system , heat shock , mutant , sigma factor , transcription (linguistics) , microbiology and biotechnology , dna binding protein , genetics , gene expression , medicine , linguistics , philosophy , pathology
Summary Bacteria and other organisms, including cyanobacteria, employ two‐component signal transducing modules comprising histidine kinases and response regulators to acclimate to changing environments. While the number and composition of these modules differ among cyanobacteria, two response regulators that contain DNA binding domains, RpaB and Rre1, are conserved in all sequenced cyanobacterial genomes and are essential for viability. Although RpaB negatively or positively regulates high light and other stress‐responsive gene expression, little is known about the function of Rre1. Here, they investigated the direct regulatory targets of Rre1 in the cyanobacterium Synechococcus elongatus PCC 7942. Chromatin immunoprecipitation and high‐density tiling array analysis were used to map Rre1 binding sites. The sites included promoter regions for chaperone genes such as dnaK2 , groESL‐1 , groEL‐2 , hspA and htpG , as well as the group 2 sigma factor gene rpoD2 . In vivo and in vitro analyses revealed that Rre1 phosphorylation level, DNA binding activity and adjacent gene transcription increased in response to heat stress. These responses were much diminished in a knock‐out mutant of Hik34, a previously identified heat shock regulator. Based on our results, we propose Hik34‐Rre1 is the heat shock‐responsive signaling module that positively regulates major chaperone and other genes in cyanobacteria.