Conserved two-component Hik34-Rre1 module directly activates heat-stress inducible transcription of major chaperone and other genes in Synechococcus elongatus PCC 7942
Conserved two-component Hik34-Rre1 module directly activates heat-stress inducible transcription of major chaperone and other genes in Synechococcus elongatus PCC 7942
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DOI：
10.1111/mmi.13624
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发表时间：
2017-04-01
影响因子：
3.6
通讯作者：
Tanaka, Kan
中科院分区：
文献类型：
--
作者：
Kobayashi, Ikki;Watanabe, Satoru;Tanaka, Kan
细菌和其他生物体，包括蓝藻，采用双组分信号转导模块，包括组氨酸激酶和反应调节剂，以适应不断变化的环境。虽然这些模块的数量和组成不同的蓝藻，两个反应调节器，包含DNA结合结构域，RpaB和Rre 1，是保守的所有测序蓝藻基因组和生存能力是必不可少的。虽然RpaB负或正调节高光和其他应激反应基因的表达，但对Rre 1的功能知之甚少。在这里，他们研究了Rre 1在蓝细菌Synechococcus elongatus PCC 7942中的直接调控靶点。染色质免疫沉淀和高密度平铺阵列分析用于映射Rre 1结合位点。这些位点包括分子伴侣基因如dnaK 2、groESL-1、groEL-2、hspA和htpG的启动子区，以及2组σ因子基因rpoD 2。体内和体外分析表明，热应激增加了Rre 1磷酸化水平，DNA结合活性和邻近基因的转录。这些反应大大减少了敲除突变体的Hik 34，以前确定的热休克调节。基于我们的研究结果，我们建议Hik 34-Rre 1是热休克反应信号模块，积极调节主要伴侣和其他基因在蓝藻。
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.