The cyanobacterial homologue of HCF136/YCF48 is a component of an early photosystem II assembly complex and is important for both the efficient assembly and repair of photosystem II in Synechocystis sp PCC 6803
The cyanobacterial homologue of HCF136/YCF48 is a component of an early photosystem II assembly complex and is important for both the efficient assembly and repair of photosystem II in Synechocystis sp PCC 6803
复制标题
DOI：
10.1074/jbc.m801917200
复制
发表时间：
2008-08-15
影响因子：
4.8
通讯作者：
Nixon, Peter J.
中科院分区：
文献类型：
--
作者：
Komenda, Josef;Nickelsen, Joerg;Nixon, Peter J.
在聚球藻PCC6803中研究了slr2034(Ycf48)基因产物在光系统II(PSII)组装和修复中的作用。YCF48(HCF136)参与了拟南芥PSII反应中心(RC)复合体的组装，但其作用机制尚不清楚。我们在这里表明，YCF48是体内两个蓝藻PSII RC类复合体的组成部分，在较大的PSII核心复合体中不存在。从脉冲标记实验来看，阻断ycf48减缓了野生型PSII复合体的形成，并导致野生型PSII核心复合体的最终水平下降，以及缺乏CP43或CP47的菌株的PSII组装复合体水平显著下降。YCF48的缺失还导致各种PSII突变体中COOH末端前体(PD1)和部分加工形式Id1的水平显著下降，仅观察到低水平的未组装成熟D1。使用裂解泛素系统的酵母双杂交分析表明，YCF48与未组装的PD1相互作用，在较小程度上与未组装的Id1相互作用，但不与未组装的成熟D1或D2相互作用。总体而言，我们的结果表明，YCF48在稳定新合成的PD1以及随后与D2-细胞色素b(559)前复合体结合方面发挥了作用，这也在本研究中得到了确认。除了在组装过程中发挥作用外，我们还首次证明了YCF48在PSII修复过程中还选择性地替代光损伤的D1。
The role of the slr2034 (ycf48) gene product in the assembly and repair of photosystem II (PSII) has been studied in the cyanobacterium Synechocystis PCC 6803. YCF48 (HCF136) is involved in the assembly of Arabidopsis thaliana PSII reaction center (RC) complexes but its mode of action is unclear. We show here that YCF48 is a component of two cyanobacterial PSII RC-like complexes in vivo and is absent in larger PSII core complexes. Interruption of ycf48 slowed the formation of PSII complexes in wild type, as judged from pulse-labeling experiments, and caused a decrease in the final level of PSII core complexes in wild type and a marked reduction in the levels of PSII assembly complexes in strains lacking either CP43 or CP47. Absence of YCF48 also led to a dramatic decrease in the levels of the COOH-terminal precursor (pD1) and the partially processed form, iD1, in a variety of PSII mutants and only low levels of unassembled mature D1 were observed. Yeast two-hybrid analyses using the split ubiquitin system showed an interaction of YCF48 with unassembled pD1 and, to a lesser extent, unassembled iD1, but not with unassembled mature D1 or D2. Overall our results indicate a role for YCF48 in the stabilization of newly synthesized pD1 and in its subsequent binding to a D2-cytochrome b(559) pre-complex, also identified in this study. Besides a role in assembly, we show for the first time that YCF48 also functions in the selective replacement of photodamaged D1 during PSII repair.