ChlH, the H subunit of the Mg-chelatase, is an anti-sigma factor for SigE in Synechocystis sp PCC 6803
ChlH, the H subunit of the Mg-chelatase, is an anti-sigma factor for SigE in Synechocystis sp PCC 6803
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DOI：
10.1073/pnas.0810040106
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发表时间：
2009-04-21
影响因子：
11.1
通讯作者：
Tanaka, Kan
中科院分区：
文献类型：
--
作者：
Osanai, Takashi;Imashimizu, Masahiko;Tanaka, Kan
尽管已经深入研究了西格玛因子的调节，但在产氧光合生物中尚未发现反西格玛因子。先前的一项研究表明，蓝藻集胞藻属的 sigma 因子 SigE。 PCC 6803 是糖分解代谢的正调节因子，在翻译后由光到暗转变激活。在本研究中，我们通过酵母双杂交筛选发现镁螯合酶 ChlH 的 H 亚基与 sigma 因子 SigE 相互作用，免疫沉淀分析表明 ChlH 在体内以光依赖性方式与 SigE 结合。我们还发现 Mg2+ 促进 SigE 和 ChlH 的相互作用并决定它们的体外定位。体外转录分析表明 ChlH 抑制 SigE 的转录活性。基于这些结果，我们提出了一个模型，其中 ChlH 作为抗 sigma 因子，在 Mg2+ 介导的过程中将光信号转换为 SigE。
Although regulation of sigma factors has been intensively investigated, anti-sigma factors have not been identified in oxygenic photosynthetic organisms. A previous study suggested that the sigma factor, SigE, of the cyanobacterium Synechocystis sp. PCC 6803, a positive regulator of sugar catabolism, is posttranslationally activated by light-to-dark transition. In the present study, we found that the H subunit of Mg-chelatase ChlH interacts with sigma factor SigE by yeast two-hybrid screening, and immunoprecipitation analysis revealed that ChlH associates with SigE in a light-dependent manner in vivo. We also found that Mg2+ promotes the interaction of SigE and ChlH and determines their localization in vitro. In vitro transcription analysis demonstrated that ChlH inhibits the transcription activity of SigE. Based on these results, we propose a model in which ChlH functions as an anti-sigma factor, transducing light signals to SigE in a process mediated by Mg2+.