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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

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06640832/
关键词：
Photosystem I Synechocystis Targeted mutagenesis PsaK 光合成 Synechocystis sp.ランソウ

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（Photosystem I，PSI）是一种多亚基的色素蛋白复合物，由10多种不同的多肽（PsaA到PsaM）组成，催化光驱动的电子从细胞色素c_6/质体蓝蛋白到铁氧还蛋白的传递。在这项研究中，我们已经产生了集胞藻PCC 6803的第一个PsaK缺陷突变株byogene-targeting，以确定PSI功能和组织中的PsaK的作用。PsaK的功能尚不清楚。使用根据从集胞藻PCC 6803基因组数据库Cyanobase获得的psaK的序列信息制备的核苷酸引物，通过PCR从集胞藻PCC 6803基因组DNA扩增含有psaK的DNA片段。将PCR片段克隆到pGEM-T载体上。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基因被赋予卡那霉素抗性的基因中断。北方印迹分析和SDS聚丙烯酰胺凝胶电泳结果表明，突变株缺乏psaK的转录和翻译产物，单位细胞基础上的叶绿素和藻胆体数量减少，表明PsaK参与了这些色素的结合。突变体的光合自养生长和光合特性与野生型相似，突变研究表明，缺少一个（或两个）PSI辅助亚基的突变体的光合作用与野生型一样活跃。PSI的辅助亚基不结合任何氧化还原活性因子，如PsaA，PsaB和PsaC。为了发现这些辅助亚基的生理意义，我们比较了突变株和野生型在各种胁迫条件下的表型。我们已经获得了一些证据表明，PsaD和PsaE是重要的保护蓝藻细胞免受光抑制和热损伤。