Bruce B D, Malkin R
Department of Plant Biology, University of California, Berkeley 94720.
Plant Cell. 1991 Feb;3(2):203-12. doi: 10.1105/tpc.3.2.203.
The biosynthesis of the cytochrome b6f complex has been studied in a mutant, no. 1073, of Lemna perpusilla that contained less than 1% of the four protein subunits when compared with a wild-type strain. RNA gel blot analyses of the mutant indicated that the chloroplast genes for cytochrome f, cytochrome b6, and subunit IV (petA, petB, and petD, respectively) are transcribed and that the petB and petD transcripts undergo their normal processing. Analysis of polysomal polyA+ RNA indicated that the level of translationally active mRNA for the nuclear-encoded Rieske Fe-S protein (petC) was reduced by greater than 100-fold in the mutant. Immunoprecipitation of in vivo labeled proteins indicated that both cytochrome f and subunit IV are synthesized and that subunit IV has a 10-fold higher rate of protein turnover in the mutant. These results are discussed in terms of the assembly of the cytochrome complex and the key role of the Rieske Fe-S protein in this process.
已在浮萍(Lemna perpusilla)的1073号突变体中研究了细胞色素b6f复合物的生物合成。与野生型菌株相比,该突变体中四种蛋白质亚基的含量不到1%。对该突变体的RNA凝胶印迹分析表明,细胞色素f、细胞色素b6和亚基IV(分别为petA、petB和petD)的叶绿体基因被转录,并且petB和petD转录本经历正常加工。对多聚核糖体多聚A + RNA的分析表明,突变体中核编码的 Rieske Fe-S 蛋白(petC)的翻译活性mRNA水平降低了100倍以上。体内标记蛋白质的免疫沉淀表明,细胞色素f和亚基IV均被合成,并且突变体中亚基IV的蛋白质周转速率高10倍。根据细胞色素复合物的组装以及 Rieske Fe-S 蛋白在此过程中的关键作用对这些结果进行了讨论。