Aberrant Attachment of Heme to Cytochrome by the Ccm System Results in a Cysteine Persulfide Linkage

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• 作者：Elizabeth B. Sawyer ; Elaine Stephens ; Stuart J. Ferguson ; James W. A. Allen ; Paul D. Barker
• 刊名：Journal of the American Chemical Society
• 出版年：2010
• 出版时间：April 14, 2010
• 年：2010
• 卷：132
• 期：14
• 页码：4974-4975
• 全文大小：139K
• 年卷期：v.132,no.14(April 14, 2010)
• ISSN：1520-5126

文摘

The system I cytochrome c maturation (Ccm) apparatus has been shown to handle a wide variety of apocytochrome substrates containing the CX_nCH heme attachment sequence, where n = 2, 3, or 4 in natural sequences. When n = 5 or 6, the apparatus also appears to handle these substrates correctly, but close inspection reveals that the resulting mature cytochromes are mixtures of species containing extra mass. We have used accurate mass spectrometry to analyze peptide digests of matured Escherichia coli cytochrome cb₅₆₂ with n = 1, 5, or 6 and shown that an extra sulfur is sometimes incorporated into the heme−protein linkage. These unprecedented, aberrant persulfide linkages may shed new light upon the mechanism of the attachment of heme to substrate apocytochrome within the Ccm complex of E. coli.