PSII-Tc protein plays an important role in dimerization of photosystem II
PSII-Tc protein plays an important role in dimerization of photosystem II
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DOI：
10.1093/pcp/pch207
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发表时间：
2004-12-01
影响因子：
4.9
通讯作者：
Ikeuchi, M
中科院分区：
文献类型：
--
作者：
Iwai, M;Katoh, H;Ikeuchi, M
我们克隆和确定的PSII基因的核苷酸序列，psbB和psbTc，从嗜热蓝细菌，细长热聚球藻菌株BP-1。PSII-Tc由psbTc编码，是蓝细菌和植物PSII核心复合物的一个跨膜小亚基。然而，其作用尚未得到充分阐明。我们产生了一个插入破坏psbTc和研究的PSII-Tc蛋白在蓝藻PSII的作用。结果表明：（1）psbTc突变体能以与野生型T.在广泛的光照条件下生长。(ii)类囊体和氧释放PSII复合物被成功地从psbTc破坏以及野生型分离。psbTc破坏剂和野生型之间的细胞，类囊体或PSII复合物的放氧活性没有显着差异。这与T.细长的(iii)单体和二聚体PSII的色谱分离显示，二聚体PSII的回收率显着降低的psbTc破坏。(iv)SDS-urea-PAGE显示突变体PSII的4.7-kDa条带完全丢失。由于该带在野生型PSII中由PSII-M和PSII-Tc组成，我们假设PSII-Tc对于PSII-M在PSII复合物中的结合是至关重要的，并且直接和间接地参与PSII的二聚化。这些结果似乎是在良好的协议与最近的结构模型的二聚PSII复合物。
We cloned and determined the nucleotide sequence of PSII genes, psbB and psbTc, from the thermophilic cyanobacterium, Thermosynechococcus elongatus strain BP-1. PSII-Tc, encoded by psbTc, is a small membrane-spanning subunit of the PSII core complex of cyanobacteria and plants. However, its role has not been fully elucidated. We generated an insertional disruptant of psbTc and studied the role of the PSII-Tc protein in cyanobacterial PSII. The following observations were made: (i) The psbTc disruptant could grow photoautotrophically at a rate similar to that of wild-type T. elongatus under a wide range of light conditions. (ii) Thylakoids and oxygen-evolving PSII complexes were successfully isolated from the psbTc disruptant as well as the wild type. There was no significant difference in the oxygen evolution activities of cells, thylakoids or PSII complexes between the psbTc disruptant and the wild type. This is in contrast to the lower activities in the other PSII mutants of T. elongatus. (iii) Chromatographic separation of monomeric and dimeric PSII revealed that recovery of dimeric PSII was dramatically reduced in the psbTc disruptant. (iv) SDS-urea-PAGE showed a complete loss of the 4.7-kDa band in the mutant PSII. Since this band in wild-type PSII consists of PSII-M and PSII-Tc, we assume that PSII-Tc is critical for the binding of PSII-M in the PSII complex and is involved directly and indirectly in the dimerization of PSII. These results appear to be in good agreement with the recent structural model of the dimeric PSII complex.