The roles of Rhodobacter sphaeroides copper chaperones PCu_AC and Sco (PrrC) in the assembly of the copper centers of the aa₃-type and the cbb₃-type cytochrome c oxidases

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• 作者：Audie K. Thompson¹ ; ^{akthompson@PVAMU.edu} ; Jimmy Gray ^{jlgray@umc.edu} ; Aimin Liu² ; ^{Feradical@gsu.edu} ; Jonathan P. Hosler ; ^{jhosler@umc.edu}
• 关键词：CCCP ; carbonylcyanide m-chlorophenylhydrazone ; CcO ; cytochrome c oxidase ; ICP-OES ; inductively coupled plasma optical emission spectroscopy ; TMPD ; N ; N ; N&prime ; N&prime ; -tetramethyl-p-phenylenediamine
• 刊名：Biochimica et Biophysica Acta (BBA)/Bioenergetics
• 出版年：2012
• 期刊代码：13_00052728
• 类别：bio
• 出版时间：June, 2012
• 卷：1817
• 期：6
• 页码：955-964
• 文件大小：739 K

摘要

The 伪 proteobacter Rhodobacter sphaeroides accumulates two cytochrome c oxidases (CcO) in its cytoplasmic membrane during aerobic growth: a mitochondrial-like aa₃-type CcO containing a di-copper Cu_A center and mono-copper Cu_B, plus a cbb₃-type CcO that contains Cu_B but lacks Cu_A. Three copper chaperones are located in the periplasm of R. sphaeroides, PCu_AC, PrrC (Sco) and Cox11. Cox11 is required to assemble Cu_B of the aa₃-type but not the cbb₃-type CcO. PrrC is homologous to mitochondrial Sco1; Sco proteins are implicated in Cu_A assembly in mitochondria and bacteria, and with Cu_B assembly of the cbb₃-type CcO. PCu_AC is present in many bacteria, but not mitochondria. PCu_AC of Thermus thermophilus metallates a Cu_A center in vitro, but its in vivo function has not been explored. Here, the extent of copper center assembly in the aa₃- and cbb₃-type CcOs of R. sphaeroides has been examined in strains lacking PCu_AC, PrrC, or both. The absence of either chaperone strongly lowers the accumulation of both CcOs in the cells grown in low concentrations of Cu^2 +. The absence of PrrC has a greater effect than the absence of PCu_AC and PCu_AC appears to function upstream of PrrC. Analysis of purified aa₃-type CcO shows that PrrC has a greater effect on the assembly of its Cu_A than does PCu_AC, and both chaperones have a lesser but significant effect on the assembly of its Cu_B even though Cox11 is present. Scenarios for the cellular roles of PCu_AC and PrrC are considered. The results are most consistent with a role for PrrC in the capture and delivery of copper to Cu_A of the aa₃-type CcO and to Cu_B of the cbb₃-type CcO, while the predominant role of PCu_AC may be to capture and deliver copper to PrrC and Cox11. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes.