Construction of cyanobacterial mutant strains which lack a specific subunit of photo system I and the characterization of their photosynthetic properties.

缺乏光系统I特定亚基的蓝藻突变株的构建及其光合特性的表征。

基本信息

批准号：
06640832
负责人：
NAKAMOTO Hitoshi
金额：
$ 1.34万
依托单位：
Saitama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

Photosystem I (PSI) is a multisubunit pigment-protein complex that consists of more than 10 different polypeptides (from PsaA to PsaM) and catalyzes light-driven electron transfer from cytochrome c_6/plastocyanin to ferredoxin. In this study, we have generated the first PsaK-deficient mutant strains of Synechocystis sp.PCC 6803 byogene-targeting in order to identify roles of PsaK in PSI function and organization. Nothing is known about the function of PsaK.DNA fragment containing psaK was amplified from the Synechocystis sp.PCC 6803 genomic DNA by PCR with using nucleotide primers made according the sequence information for psaK which was obtained from Cyanobase, the database on the genome of Synechocystis sp.PCC 6803. The PCR fragment was then cloned into pGEM-T vector. A mutant strain lacking PsaK was generated by transforming the wild type cells with cloned DNA in which psaK gene was interrupted by a gene conferring resistance to kanamycin. Northern blot analysis and SDS polyacrylamide gel electrophoresis revealed that the mutant strain lacked both the transcript and translation products of psaK.The amount of chlorophyll and phycobilisome per cell basis was reduced, suggesting the involvement of PsaK with the binding of those pigments. However, photoautotrophic growth and photosynthetic characteristics of the mutant strain were similar to those of the wild type.The mutational studies have shown that mutants lacking one (or two) of the accessory subunits of PSI photosynthesize as actively as the wild type. The accessory subunits of PSI do not bind any redox-active cnfactors like PsaA,PsaB and PsaC.In order to find physiological importance of these accessory subunit, we compared phenotypes of the mutant strains with that of the wild type under various stress conditions. We have obtained some evidences which demonstrate that PsaD and PsaE are important for the protection of cyanobacterial cells from photoinhibition and heat-damage.

光系统I（PSI）是一种多生育色素 - 蛋白质复合物，由10多种不同的多肽（从PSAA到PSAM）组成，并催化从细胞色素C_6/Plastocyanin到Ferredoxin的光驱动电子转移。在这项研究中，我们生成了第一个PSAK缺陷型突变体菌株SPCC.PCC 6803 Byogene-taggogenting，以鉴定PSAK在PSI功能和组织中的作用。 PSAK的功能对含有PSAK的DNA片段的功能尚无了解，可以通过PCR与PCR使用PSAK的核苷酸引物通过PSAK获得的核苷酸引物，从Cyanobase获得的核苷酸引物（从cyanobase获得的核苷酸引物）中，该序列是从Syechocystis spcc.pgcc 6803的基因组中获得的。通过用克隆的DNA转化野生型细胞来产生缺乏PSAK的突变菌株，其中PSAK基因被赋予卡纳米霉素的抗性的基因中断。 Northern印迹分析和SDS聚丙烯酰胺凝胶电泳表明，突变菌株既缺乏PSAK的转录物和翻译产物。每个细胞的叶绿素和植物质体的量减少，这表明PSAK与这些颜料的结合有关。然而，突变菌株的光自营养生长和光合作用特征与野生型相似。突变研究表明，缺乏PSI光合作用的一个（或两个）辅助亚基的突变体像野生型一样活跃地化为野生型。 PSI的辅助亚基不结合任何氧化还原活性的CNFACTOR，例如PSAA，PSAB和PSAC。为了找到这些辅助亚基的生理重要性，我们将突变菌株的表型与在各种应力条件下的野生型相结合。我们获得了一些证据，这些证据表明PSAD和PSAE对于保护蓝细菌细胞免受光抑制和热损伤至关重要。