Ccl2 (CcmH) is a membrane-anchored thiol-disulfide oxidoreductase of the cytochrome c maturation machinery. Its periplasmic redox domain forms and resolves thiol-exchange intermediates with apocytochrome c and CcmG, coordinating cysteine availability with stereospecific heme ligation in the CcmFHI complex.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005886 plasma membrane | IEA GO_REF:0000118 | ACCEPT | Summary: CcmH anchors its periplasmic redox domain in the cytoplasmic membrane. Reason: The conserved single C-terminal transmembrane helix and periplasmic redox domain support this location. TreeGrafter inference is consistent with target architecture; it is not evidence of heme transport. The frozen target is SB1003; the primary work uses tagged/truncated R. capsulatus proteins and MT1131-derived complementation backgrounds. This is a conserved-role inference, not a direct assay of an unmodified SB1003 protein; construct provenance is documented in the source analysis. Supporting Evidence: PMID:28634234 CcmH has a single C-terminal TM helix and a periplasmic domain containing a conserved LRC XX CQ active site. |
| GO:0042597 periplasmic space | IEA GO_REF:0000044 | MODIFY | Summary: CcmH thiol exchange occurs in the outer membrane-bounded periplasm. Reason: The conserved single C-terminal transmembrane helix and periplasmic redox domain support this location. TreeGrafter inference is consistent with target architecture; it is not evidence of heme transport. The frozen target is SB1003; the primary work uses tagged/truncated R. capsulatus proteins and MT1131-derived complementation backgrounds. This is a conserved-role inference, not a direct assay of an unmodified SB1003 protein; construct provenance is documented in the source analysis. Proposed replacements: outer membrane-bounded periplasmic space Supporting Evidence: PMID:28634234 CcmH has a single C-terminal TM helix and a periplasmic domain containing a conserved LRC XX CQ active site. |
| GO:0015036 disulfide oxidoreductase activity | IC PMID:28634234 The thioreduction component CcmG confers efficiency and the ... | NEW | Summary: CcmH mediates thiol-disulfide exchange with apocytochrome c and CcmG. Reason: Purified R. capsulatus CcmH Cys variants participate in quantified thiol-disulfide exchange; this adds the missing molecular activity rather than inferring catalysis from essentiality. The stereospecific ligation sequence is a mechanistic model supported by differential reactivity, not a fully observed native intermediate pathway. The frozen target is SB1003; the primary work uses tagged/truncated R. capsulatus proteins and MT1131-derived complementation backgrounds. This is a conserved-role inference, not a direct assay of an unmodified SB1003 protein; construct provenance is documented in the source analysis. Supporting Evidence: PMID:28634234 Cys-45 of CcmH and Cys-34 of apocytochrome c are most likely to form this mixed disulfide bond PMID:28634234 CcmG can efficiently reduce the disulfide bond of apocytochrome c and also resolve a mixed disulfide bond formed between apocytochrome c and CcmH. file:RHOCB/ccl2/ccl2-source-analysis/construct-scope.md The SB1003 reviews therefore transfer conserved molecular roles with explicit construct/strain limits and do not claim an unmodified SB1003 assay. |
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Download this section (compressed HTML)Q: Can the complete assayed construct sequence be matched to this SB1003 accession, and can the proposed intermediates be measured in the native strain?
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