Roles of molecular chaperones for regulation of genes and assembly of photosynthetic apparatus

1.新型分子伴侣对蓝藻groESL 1转录的正向控制，Orf7.5Orf7.5是一个正性转录因子，它通过与主要的sigma因子相互作用，提高聚球藻7942的groESL 1启动子的活性，特别是在热激条件下。休克诱导来自硫化聚球藻的hspA基因编码一种小的热休克蛋白。3. HspA的细胞功能对集胞藻（Synechocystis sp. PCC 6803）及其hspA缺失突变株的比较分析表明，hspA参与了盐胁迫的调控。将组成型表达HspA的聚球藻属菌株ECT 16 -1与参考菌株ECT进行比较，研究了HspA在应激条件下的作用。HspA赋予蓝藻在高温或强氧化条件下超微结构的稳定性 ...更多信息 4. HtpG的细胞功能我们阐明了组成型表达的HspA是否可以在功能上取代聚球藻PCC 7942中的HtpG。在胁迫条件下，HspA不能改善htpG突变体的缺陷，表明htpG的细胞功能可能与HspA不同。5.分子伴侣在藻胆体组装中的作用我们发现HspA在体外与聚球藻7942的藻蓝蛋白直接相互作用。这些结果表明，分子伴侣通过稳定藻蓝蛋白和连接多肽在藻胆体组装中起着重要作用。6.蓝藻isiABC操纵子在抗氧化和热胁迫中的作用isiAB操纵子编码CP 43 '和黄素氧还蛋白，形成光合机构。我们发现，isiABC操纵子不仅在铁胁迫下发挥重要作用，而且在氧化和热胁迫等多重胁迫下也发挥重要作用。少

1.A positive control of the cyanobacterial groESL1 transcription by a novel molecular chaperone, Orf7.5Orf7.5 was a positive transcription factor which increases the activity of the groESL1 promoter of Synechococcus sp. PCC 7942 especially under heat shock conditions by interacting with the major sigma factor.2.Post-transcriptional regulation of the cyanobacterial hspA heat-shock inductionThe hspA gene from Synechococcus vulcanus encodes a small heat-shock protein. We showed that the hspA heat-shock induction is self-controlled post-transcriptionally.3.Cellular functions of HspAComparative analyses of the wild-type Synechocystis sp. PCC 6803 and its hspA null mutant strain showed that hspA is involved in salt-stress management. The role of HspA under stress conditions was investigated comparing Synechococcus strain ECT16-1, which constitutively expresses HspA, with the reference strain ECT. HspA conferred the cyanobacterium ultrastructural stability under high temperature or intensive … More light stress.4.Cellular functions of HtpGWe elucidated whether constitutive expression of HspA can functionally replace HtpG in Synechococcus sp. PCC 7942. It did not improve defects of an htpG mutant under stress conditions, indicating that cellular function of HtpG may differ from that of HspA.5.Roles of molecular chaperone for the phycobilisome assemblyWe showed that HspA interacts directly with phycocyanins from Synechococcus sp. PCC 7942 in vitro. We also showed a specific interaction between a linker polypeptide of phycobilisome and HtpG These results indicate that the molecular chaperones play important roles in the phycobilisome assembly by stabilizing phycocyanins and the linker polypeptide.6.Roles of the cyanobacterial isiABC operon in protection from oxidative and heat stressesThe isiAB operon encodes CP43' and flavodoxin which form the photosynthetic apparatus. We showed that the isiABC operon plays essential roles not only under iron stress, but also under multiple stresses such as oxidative and heat stresses. Less