Mechanisms of Mitochondrial Holocytochrome c Synthase and the Key Roles Played by Cysteines and Histidine of the Heme Attachment Site, Cys-XX-Cys-His

Babbitt, Shalon E.; Francisco, Brian San; Mendez, Deanna L.; Lukat-Rodgers, Gudrun S.; Rodgers, Kenton R.; Bretsnyder, Eric C.; Kranz, Robert G.

doi:10.1074/jbc.m114.593509

Cited by 24 publications

(66 citation statements)

References 32 publications

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“…3D, panel iv, red line). Complexes with C18A cyt c form a single thioether with heme at Cys 15 and yield an ␣ peak at ϳ560 nm (27,31). The above results suggest that ⌬M13 cyt c may only have Cys 18 covalently attached when in complex with HCCS.…”

Section: Cyt C Variants Containing N-terminal Residue Deletions Form mentioning

confidence: 61%

“…Residue numbering represents that of full-length human cyt c sequence with the initiating methionine as position 1. B, PyMOL-generated structure of human cyt c N terminus ( substitutions are trapped in complex with HCCS, whereas the triple mutant (in which both cysteines and the histidine residue are changed) is not (31). We used this co-purification approach to determine whether ⌬M13 cyt c was defective in recognition by HCCS (step 2) or perhaps another step in maturation.…”

Section: Cyt C Variants Containing N-terminal Residue Deletions Form mentioning

confidence: 99%

“…Complexes with HCCS-Following coexpression, a fraction of cyt c can be co-purified in complex with membrane-bound HCCS (27,31,32), effectively trapping a transitional intermediate during the maturation process. For example, single cysteine or histidine (from the CXXCH motif) FIGURE 2.…”

Section: Cyt C Variants Containing N-terminal Residue Deletions Form mentioning

confidence: 99%

“…We used this co-purification approach to determine whether ⌬M13 cyt c was defective in recognition by HCCS (step 2) or perhaps another step in maturation. HCCS complexes containing cyt c exhibit spectral characteristics that provide insight into the heme environment within the complex (31). To determine whether cyt c ␣ helix-1 deletion variants interact with HCCS, we purified recombinantly expressed HCCS from Escherichia coli membranes and probed for co-purified cyt c (Fig.…”

Section: Cyt C Variants Containing N-terminal Residue Deletions Form mentioning

confidence: 99%

“…Cys 15 and Cys 18 supply the reactive thiol side chains that, respectively, form thioether attachments to the 2-and 4-vinyl groups of heme (2,3). Recently, it was shown that His 19 is recognized as one of two axial heme ligands in the HCCS-cyt c complex (31); the other is His 154 of HCCS (27). Furthermore, cyt c His 19 plays crucial roles in facilitating thioether formation at the active site of HCCS (31).…”

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Molecular Basis Behind Inability of Mitochondrial Holocytochrome c Synthase to Mature Bacterial Cytochromes

Babbitt

Hsu

Kranz

2016

Journal of Biological Chemistry

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Mitochondrial holocytochrome c synthase (HCCS) is required for cytochrome c (cyt c) maturation and therefore respiration. HCCS efficiently attaches heme via two thioethers to CXXCH of mitochondrial but not bacterial cyt c even though they are functionally conserved. This inability is due to residues in the bacterial cyt c N terminus, but the molecular basis is unknown. Human cyts c with deletions of single residues in ␣ helix-1, which mimic bacterial cyt c, are poorly matured by human HCCS. Focusing on ⌬M13 cyt c, we co-purified this variant with HCCS, demonstrating that HCCS recognizes the bacterial-like cytochrome. Although an HCCS-WT cyt c complex contains two covalent links, HCCS-⌬M13 cyt c contains only one thioether attachment. Using multiple approaches, we show that the single attachment is to the second thiol of C 15 SQC 18 H, indicating that ␣ helix-1 is required for positioning the first cysteine for covalent attachment, whereas the histidine of CXXCH positions the second cysteine. Modeling of the N-terminal structure suggested that the serine residue (of CSQCH) would be anchored where the first cysteine should be in ⌬M13 cyt c. An engineered cyt c with a CQCH motif in the ⌬M13 background is matured at higher levels (2-3-fold), providing further evidence for ␣ helix-1 positioning the first cysteine. Bacterial cyt c biogenesis pathways (Systems I and II) appear to recognize simply the CXXCH motif, not requiring ␣ helix-1. Results here explain mechanistically how HCCS (System III) requires an extended region adjacent to CXXCH for maturation.

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Section: Cyt C Variants Containing N-terminal Residue Deletions Form mentioning

confidence: 61%

Section: Cyt C Variants Containing N-terminal Residue Deletions Form mentioning

confidence: 99%

Section: Cyt C Variants Containing N-terminal Residue Deletions Form mentioning

confidence: 99%

Section: Cyt C Variants Containing N-terminal Residue Deletions Form mentioning

confidence: 99%

mentioning

confidence: 99%

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Molecular Basis Behind Inability of Mitochondrial Holocytochrome c Synthase to Mature Bacterial Cytochromes

Babbitt

Hsu

Kranz

2016

Journal of Biological Chemistry

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Cofactor Assembly of Cytochrome bc 1 -b 6 f Complexes

Cline

Gabilly

Subrahmanian

et al. 2016

Advances in Photosynthesis and Respiration

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Bioenergetics Theory and Components | Cytochrome c Assembly

Das

Hamel

2021

Encyclopedia of Biological Chemistry III

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Mechanisms of Mitochondrial Holocytochrome c Synthase and the Key Roles Played by Cysteines and Histidine of the Heme Attachment Site, Cys-XX-Cys-His

Cited by 24 publications

References 32 publications

Molecular Basis Behind Inability of Mitochondrial Holocytochrome c Synthase to Mature Bacterial Cytochromes

Molecular Basis Behind Inability of Mitochondrial Holocytochrome c Synthase to Mature Bacterial Cytochromes

Cofactor Assembly of Cytochrome bc 1 -b 6 f Complexes

Bioenergetics Theory and Components | Cytochrome c Assembly

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