THE ASSEMBLY OF CYTOCHROME B(6)/F COMPLEXES - AN APPROACH USING GENETIC-TRANSFORMATION OF THE GREEN-ALGA CHLAMYDOMONAS-REINHARDTII
THE ASSEMBLY OF CYTOCHROME B(6)/F COMPLEXES - AN APPROACH USING GENETIC-TRANSFORMATION OF THE GREEN-ALGA CHLAMYDOMONAS-REINHARDTII
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DOI：
10.1002/j.1460-2075.1994.tb06350.x
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发表时间：
1994-03-01
期刊：
影响因子：
11.4
通讯作者：
WOLLMAN, FA
中科院分区：
文献类型：
--
作者：
KURAS, R;WOLLMAN, FA
作为细胞色素B（6）/f复合物的生物发生研究的一种方法，我们的特点是其组成亚基的行为在莱茵衣藻突变株轴承明确定义的突变。为此，我们构建了三个缺失突变株，每个缺失一个主要叶绿体pet基因：Delta petA、Delta petB和Delta petD株分别不能合成cyt f、cyt B（6）和亚基IV（suIV）。蛋白质印迹分析、脉冲标记和脉冲追踪实验使我们能够比较各种菌株中剩余的cyt B（6）/f亚基的细胞积累、合成速率和周转。我们发现，cyt B（6）和suIV的合成速率与复合物中其他亚基的存在无关，但它们在类囊体膜中的稳定是一个协调的过程，suIV的稳定性明显依赖于cyt bg的存在。成熟的cyt f在缺乏suIV或cyt B的情况下是稳定的（6），但在这些条件下其合成速率严重降低。我们的结论是叶绿体编码的cyt B（6）/f复合物的亚基的化学计量积累的结果从两个调节过程：翻译后调节导致蛋白水解处理未组装的cyt bb和suIV和共翻译（或早期翻译后）的调节，确保生产cyt f旁边的网站的组装。
As an approach to the study of the biogenesis of the cytochrome b(6)/f complex, we characterized the behaviour of its constitutive subunits in mutant strains of Chlamydomonas reinhardtii bearing well-defined mutations. To this end, we have constructed three deletion mutant strains, each lacking one of the major chloroplast pet genes: the Delta petA, Delta petB and Delta petD strains were unable to synthesize cyt f, cyt b(6) and subunit IV (suIV) respectively. Western blotting analysis, pulse-labelling and pulse - chase experiments allowed us to compare the cellular accumulation, the rates of synthesis and the turnover of the cyt b(6)/f subunits remaining in the various strains. We show that the rates of synthesis of cyt b(6) and suIV are independent of the presence of the other subunits of the complex but that their stabilization in the thylakoid membranes is a concerted process, with a marked dependence of suIV stability on the presence of cyt bg In contrast, mature cyt f was stable in the absence of either suIV or cyt b(6) but its rate of synthesis was severely decreased in these conditions. We conclude that the stoichiometric accumulation of the chloroplast-encoded subunits of the cyt b(6)/f complex results from two regulation processes: a posttranslational regulation leading to the proteolytic disposal of unassembled cyt bb and suIV and a co-translational (or early post-translational) regulation which ensures the production of cyt f next to its site of assembly.