Functional analysis of a divergent system II protein, Ccs1, involved in c-type cytochrome biogenesis
Functional analysis of a divergent system II protein, Ccs1, involved in c-type cytochrome biogenesis
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DOI：
10.1074/jbc.m208652200
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发表时间：
2003-01-24
影响因子：
4.8
通讯作者：
Merchant, S
中科院分区：
文献类型：
--
作者：
Dreyfuss, BW;Hamel, PP;Merchant, S
Ccs1基因编码C型C型细胞色素生物发生途径中一个高度分化的新成分，由先前在莱茵衣藻中定义的CCS1基因编码。利用PhoA和lacZpha细菌拓扑仪推导出聚球藻的拓扑模型。6803 Ccs1同源基因，CCSB。CCSB和Ccs1类似，在其C端有一个很大的可溶腔结构域，该结构域通过蛋白质N-末端的三个紧密分布的跨膜结构域连接在类囊体膜上。对CCS1等位基因的分子分析表明，整个C端的可溶性域对于CCS1的功能是必不可少的，基质环在体内似乎是重要的，至少对CCS1的维持是重要的。定点突变分析表明，c型细胞色素组装需要位于最后一个跨膜区的单个组氨酸(His(274))，而不是必需的半胱氨酸残基(Cys(199))。Ccs1在CCs2、CCs3、CCs4和CCSA菌株中的积累减少，因此建议与其他CCS组分相互作用。
The Ccs1 gene, encoding a highly divergent novel component of a system II type c-type cytochrome biogenesis pathway, is encoded by the previously defined CCS1 locus in Chlamydomonas reinhardtii. phoA and lacZalpha bacterial topological reporters were used to deduce a topological model of the Synechocystis sp. 6803 Ccs1 homologue, CcsB. CcsB, and therefore by analogy Ccs1, possesses a large soluble lumenal domain at its C terminus that is tethered in the thylakoid membrane by three closely spaced transmembrane domains in the N-terminal portion of the protein. Molecular analysis of ccs1 alleles reveals that the entire C-terminal soluble domain is essential for Ccs1 function and that a stromal loop appears to be important in vivo, at least for maintenance of Ccs1. Site-directed mutational analysis reveals that a single histidine (His(274)) within the last transmembrane domain, preceding the large lumenal domain, is required for c-type cytochrome assembly, whereas an invariant cysteine residue (Cys(199)) is shown to be nonessential. Ccs1 is proposed to interact with other Ccs components based on its reduced accumulation in ccs2, ccs3, ccs4, and ccsA strains.