Title

Comparing substrate specificity between cytochrome c maturation and cytochrome c heme lyase systems for cytochrome c biogenesis

Document Type

Article

Publication Date

4-1-2011

Abstract

Hemes c are characterized by their covalent attachment to a polypeptide via a widely conserved CXXCH motif. There are multiple biological systems that facilitate heme c biogenesis. System I, the cytochrome c maturation (CCM) system, is found in many bacteria and is commonly employed in the maturation of bacterial cytochromes c in Escherichia coli-based expression systems. System III, cytochrome c heme lyase (CCHL), is an enzyme found in the mitochondria of many eukaryotes and is used for heterologous expression of mitochondrial holocytochromes c. To test CCM specificity, a series of Hydrogenobacter thermophilus cytochrome c552 variants was successfully expressed and matured by the CCM system with CXnCH motifs where n = 1-4, further extending the known substrate flexibility of the CCM system by successful maturation of a bacterial cytochrome c with a novel CXCH motif. Horse cytochrome c variants with both expanded and contracted attachment motifs (n = 1-3) were also tested for expression and maturation by both CCM and CCHL, allowing direct comparison of CCM and CCHL substrate specificities. Successful maturation of horse cytochrome c by CCHL with an extended CXXXCH motif was observed, demonstrating that CCHL shares the ability of CCM to mature hemes c with extended heme attachment motifs. In contrast, two single amino acid mutants were found in horse cytochrome c that severely limit maturation by CCHL, yet were efficiently matured with CCM. These results identify potentially important residues for the substrate recognition of CCHL. © The Royal Society of Chemistry.

Comments

Kleingardner, J. G., & Bren, K. L. (2011). Comparing substrate specificity between cytochrome c maturation and cytochrome c heme lyase systems for cytochrome c biogenesis. Metallomics, 3(4), 396. https://doi.org/10.1039/c0mt00086h

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