A brownian dynamics study of the interactions of the luminal domains of the cytochrome b6f complex with plastocyanin and cytochrome c6:: The effects of the Rieske FeS protein on the interactions
A brownian dynamics study of the interactions of the luminal domains of the cytochrome b6f complex with plastocyanin and cytochrome c6:: The effects of the Rieske FeS protein on the interactions
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DOI：
10.1529/biophysj.106.085936
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发表时间：
2006-10-01
影响因子：
3.4
通讯作者：
Gross, Elizabeth L.
中科院分区：
文献类型：
--
作者：
Haddadian, Esmael J.;Gross, Elizabeth L.
来自莱茵衣藻的细胞色素b(6)f复合物（cyt b(6)f）、质体青素（PC）和细胞色素c(6) （cyt c(6)）结构的可用性使我们第一次能够模拟该复合物（包括cyt f和Rieske FeS蛋白）及其氧化还原伙伴在同一物种中的腔域之间的电子转移相互作用。我们还生成了一个模型结构，其中Rieske蛋白的FeS中心比晶体结构中观察到的更靠近cyt f的血红素，并研究了它与PC和cyt c的相互作用(6)。我们的数据显示，在原始晶体结构和我们模拟的cyt b(6)f复合物结构中，Rieske蛋白都不会对PC或cyt c(6)在cyt f上的结合位置或取向产生物理干扰。无论是否存在Rieske蛋白，PC都以相同的取向停靠在cyt f上，这与之前报道的cyt f和PC复合物的核磁共振结构非常吻合。当Rieske蛋白的FeS中心靠近cyt - f的血红素时，甚至可以提高相互作用率。使用在184-191环中修饰的cyt - f进行的研究表明，在决定复合体形成率方面，cyt - f结构比Rieske蛋白的存在或不存在或其相对于cyt - f的位置更重要。
The availability of the structures of the cytochrome b(6)f complex (cyt b(6)f), plastocyanin (PC), and cytochrome c(6) (cyt c(6)) from Chlamydomonas reinhardtii allowed us, for the first time, to model electron transfer interactions between the luminal domains of this complex (including cyt f and the Rieske FeS protein) and its redox partners in the same species. We also generated a model structure in which the FeS center of the Rieske protein was positioned closer to the heme of cyt f than observed in the crystal structure and studied its interactions with both PC and cyt c(6). Our data showed that the Rieske protein in both the original crystal structure and in our modeled structure of the cyt b(6)f complex did not physically interfere with binding position or orientation of PC or cyt c(6) on cyt f. PC docked on cyt f with the same orientation in the presence or the absence of the Rieske protein, which matched well with the previously reported NMR structures of complexes between cyt f and PC. When the FeS center of the Rieske protein was moved close to the heme of cyt f, it even enhanced the interaction rates. Studies using a cyt f modified in the 184-191 loop showed that the cyt f structure is a more important factor in determining the rate of complex formations than is the presence or the absence of the Rieske protein or its position with respect to cyt f.