Cardiolipin Deficiency in Rhodobacter sphaeroides Alters the Lipid Profile of Membranes and of Crystallized Cytochrome Oxidase, but Structure and Function Are Maintained

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• 作者：Xi Zhang ; Banita Tamot ; Carrie Hiser ; Gavin E. Reid ; Christoph Benning ; Shelagh Ferguson-Miller
• 刊名：Biochemistry
• 出版年：2011
• 出版时间：May 17, 2011
• 年：2011
• 卷：50
• 期：19
• 页码：3879-3890
• 全文大小：1126K
• 年卷期：v.50,no.19(May 17, 2011)
• ISSN：1520-4995

文摘

Many recent studies highlight the importance of lipids in membrane proteins, including in the formation of well-ordered crystals. To examine the effect of changes in one lipid, cardiolipin, on the lipid profile and the production, function, and crystallization of an intrinsic membrane protein, cytochrome c oxidase, we mutated the cardiolipin synthase (cls) gene of Rhodobacter sphaeroides, causing a >90% reduction in cardiolipin content in vivo and selective changes in the abundances of other lipids. Under these conditions, a fully native cytochrome c oxidase (CcO) was produced, as indicated by its activity, spectral properties, and crystal characteristics. Analysis by MALDI tandem mass spectrometry (MS/MS) revealed that the cardiolipin level in CcO crystals, as in the membranes, was greatly decreased. Lipid species present in the crystals were directly analyzed for the first time using MS/MS, documenting their identities and fatty acid chain composition. The fatty acid content of cardiolipin in R. sphaeroides CcO (predominantly 18:1) differs from that in mammalian CcO (18:2). In contrast to the cardiolipin dependence of mammalian CcO activity, major depletion of cardiolipin in R. sphaeroides did not impact any aspect of CcO structure or behavior, suggesting a greater tolerance of interchange of cardiolipin with other lipids in this bacterial system.