Regulation of expression of heat-shock proteins in cyanobacteria and studies on multi-chaperone complexes

蓝藻热激蛋白表达调控及多伴侣复合物研究

基本信息

批准号：
13640640
负责人：
NAKAMOTO Hitoshi
金额：
$ 2.24万
依托单位：
SAITAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640640/
关键词：
Cyanobacteria Heat-shock protein Molecular chaperone Gene expression Sigma factor HtpG HtpG 発現調節

项目摘要

1. Regulation of transcription of cyanobacterial heat-shock protein (Hsp) genes(1) A novel Hsp, Orf7.5, did not bind to 5'-upstream region of groEL operon from Synechococcus PCC 7942, but interacted with the major sigma factor, enabling it to bind to the region. We postulate that Orf7.5 together with the major sigma factor is involved in a positive regulation of the operon. (2) An hrcA disruptant of Synchocystis PCC 6803 was constructed. With the mutant, we showed that the groEL genes are regulated by a negative mechanism (CIRCE/HrcA system) and a positive one that is yet to be clarified. (3) We detected a protein in the unstressed cells of the thermophilic cyanobacteriurn Synechococcus that specifically binds to a 5'-untranslated region of the hspA gene that encodes a small Hsp homologue. The time course of the DNA binding by the protein and the hspA mRNA level were inversely correlated. (4) The heat shock response is generally characteirized by an immediate, intense and transient activation of gene expression. We found that light modulates these characteristics of the heat shock response in cyanobacteria.2. Post-transcriptional regulation of heat shock genes.A downstream box (DB) sequence was found to exist in the coding sequence of the hspA gene. We postulated that the interaction of DB with 16S rRNA results in the stabilization of the hspA mRNA and the increase of its translation.3. Cellular functions of HtpGPhenotypic analyzes of an htpG disruptant of Synechococcus PCC 7942 showed that HtpG plays roles in cold acclimation and protection from oxidative stress as well as in thermo-tolerance.4. Multi-chaperone complexA novel, high-molecular-weight complex containing GroEL, DnaK and an unknown 48-kDa protein accumulated at 16℃, but the accumulation was strongly inhibited in the htpG disruptant, indicating that HtpG is involved in the formation of the complex.

1。调节蓝细菌热休克蛋白（HSP）基因的转录（1）新型的HSP ORF7.5，与Synechoccus PCC 7942的Groel Operaon的5'上游区域没有结合，但与主要的Sigma因子相互作用，使其与该区域结合。我们假设ORF7.5与主要的Sigma因子一起参与了操纵子的积极调节。（2）构建了同步藻PCC 6803的HRCA扰动。使用该突变体，我们表明凹槽基因受负机制（CIRCE/HRCA系统）和尚未澄清的阳性调节。（3）我们检测到嗜热蓝细菌的无重理细胞中的一种蛋白质，该细胞特异性结合了编码小HSP同源物的HSPA基因的5'-非翻译区域。蛋白质和HSPA mRNA水平的DNA结合的时间过程成反比。（4）热休克反应通常以基因表达的直接，强烈和短暂的激活为特征。我们发现，光调节了蓝细菌中热休克反应的这些特征2。热休克基因的转录后调节。在HSPA基因的编码序列中发现了下游框（DB）序列。我们假定DB与16S rRNA的相互作用导致HSPA mRNA的稳定及其翻译的增加。3。 HTPGNOTYPIC PCC 7942的HTPG扰动性的HTPGNOTYPIC分析的细胞功能表明，HTPG在冷适应和保护氧化物胁迫以及在热耐受性方面起着作用。4。多伴侣复合物小说，高分子重量复合物，含有凹槽，DNAK和未知的48 kDa蛋白，在16℃下积累，但在HTPG扰动中，积累严重抑制，这表明HTPG参与该复合物的形成。