N-terminal domain of cytochrome c-type biogenesis protein CcmH and related proteins
Cytochrome c-type biogenesis protein CcmH is a membrane-anchored thiol-oxidoreductase that is essential in the maturation of c-type cytochromes. CcmH consists of an N-terminal catalytic domain with the active site CXXC motif and a C-terminal domain of unknown function which is predicted to contain TPR-like repeats. Other members of this family include NrfF, CycL, and Ccl2.
Comment:The catalytic cysteine residues of the conserved CXXC motif, located in a long loop connecting the first two helices, form a disulfide bond in the oxidized enzyme. Both cysteines are required for cytochrome c maturation during aerobic growth, whereas only the second cysteine is required for cytochrome c maturation during anaerobic growth.