Psb28 Protein Is Involved in the Biogenesis of the Photosystem II Inner Antenna CP47 (PsbB) in the Cyanobacterium Synechocystis sp PCC 6803
Psb28 Protein Is Involved in the Biogenesis of the Photosystem II Inner Antenna CP47 (PsbB) in the Cyanobacterium Synechocystis sp PCC 6803
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DOI：
10.1104/pp.108.130039
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发表时间：
2009-02-01
期刊：
影响因子：
7.4
通讯作者：
Komenda, Josef
中科院分区：
文献类型：
--
作者：
Dobakova, Marika;Sobotka, Roman;Komenda, Josef
在蓝细菌集胞藻PCC 6803中研究了Psb 28蛋白在光系统II（PSII）复合物的结构和功能中的作用。该蛋白质定位在膜部分，而大部分的蛋白质被检测为未组装的蛋白质，一小部分被发现在PSII核心复合物缺乏的CP 43天线（RC 47）。Psb 28与RC 47的关联通过使用镍亲和层析从含有Psb 28的组氨酸标记的衍生物的菌株中优先分离RC 47来进一步证实。然而，亲和纯化的级分也含有少量的未组装的PSII内天线CP 47绑定到Psb 28-组氨酸，表明Psb 28和CP 47之间的结构关系。一个psb 28缺失突变体表现出较慢的自养生长比野生型，虽然没有Psb 28不影响PSII的功能特性。突变体表现出加快营业额的D1蛋白，更快的PSII修复，并减少PSI的细胞内容。放射性标记揭示了在没有Psb 28的情况下CP 47和PSI亚基PsaA/PsaB的合成的限制。突变体细胞含有高水平的镁原卟啉IX甲酯，降低水平的原叶绿素，并释放大量的原卟啉IX到培养基中，表明在环化步骤中抑制叶绿素（Chl）的生物合成，产生等环E。总之，我们的研究结果表明，Psb 28的重要性，合成的叶绿素和/或脱辅基蛋白的叶绿素结合蛋白CP 47和PsaA/PsaB。
The role of the Psb28 protein in the structure and function of the photosystem II (PSII) complex has been studied in the cyanobacterium Synechocystis sp. PCC 6803. The protein was localized in the membrane fraction and, whereas most of the protein was detected as an unassembled protein, a small portion was found in the PSII core complex lacking the CP43 antenna (RC47). The association of Psb28 with RC47 was further confirmed by preferential isolation of RC47 from the strain containing a histidine-tagged derivative of Psb28 using nickel-affinity chromatography. However, the affinity-purified fraction also contained a small amount of the unassembled PSII inner antenna CP47 bound to Psb28-histidine, indicating a structural relationship between Psb28 and CP47. A psb28 deletion mutant exhibited slower autotrophic growth than wild type, although the absence of Psb28 did not affect the functional properties of PSII. The mutant showed accelerated turnover of the D1 protein, faster PSII repair, and a decrease in the cellular content of PSI. Radioactive labeling revealed a limitation in the synthesis of both CP47 and the PSI subunits PsaA/PsaB in the absence of Psb28. The mutant cells contained a high level of magnesium protoporphyrin IX methylester, a decreased level of protochlorophyllide, and released large quantities of protoporphyrin IX into the medium, indicating inhibition of chlorophyll (Chl) biosynthesis at the cyclization step yielding the isocyclic ring E. Overall, our results show the importance of Psb28 for synthesis of Chls and/or apoproteins of Chl-binding proteins CP47 and PsaA/PsaB.