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Literature summary for 1.7.2.2 extracted from

  • Fu, H.; Jin, M.; Wan, F.; Gao, H.
    Shewanella oneidensis cytochrome c maturation component CcmI is essential for heme attachment at the non-canonical motif of nitrite reductase NrfA (2015), Mol. Microbiol., 95, 410-425 .
    View publication on PubMed
Search for more literature for 1.7.2.2

Cloned(Commentary)

Cloned (Comment) Organism
recombinant expression of wild-type and mutant enzymes in Escherichia coli Shewanella oneidensis

Protein Variants

Protein Variants Comment Organism
K119H site-directed mutagensis, mutation of the essential lysine residue of the non-canonical HBM (CX2CK), inactive mutant. The mutant NrfA protein displays a similar pattern of rapid degradation like the wild-type without maturation Shewanella oneidensis
K119L site-directed mutagensis, mutation of the essential lysine residue of the non-canonical HBM (CX2CK), inactive mutant. The mutant NrfA protein displays a similar pattern of rapid degradation like the wild-type without maturation Shewanella oneidensis
additional information costruction of a DELTAnrfA mutant enzyme knockout strain, expression of the wild-type enzyme from vector pHG101 can restore the enzyme activity, but not expression of enzyme mutants K119L and K119H Shewanella oneidensis

General Stability

General Stability Organism
NrfASo is unstable unless heme attachment is timely accomplished Shewanella oneidensis

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
nitrite + 6 ferrocytochrome c + 7 H+ Shewanella oneidensis
-
 NH3 + 2 H2O + 6 ferricytochrome c
-
 ?

Organism

Organism UniProt Comment Textmining
Shewanella oneidensis Q8EHC7
-
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
nitrite + 6 ferrocytochrome c + 7 H+
-
 Shewanella oneidensis NH3 + 2 H2O + 6 ferricytochrome c
-
 ?

Synonyms

Synonyms Comment Organism
nitrite reductase
-
 Shewanella oneidensis
NrfA
-
 Shewanella oneidensis

Cofactor

Cofactor Comment Organism Structure
cytochrome c an enzyme-bound c-type cytochrome with a non-canonical CX2CK motif. CcmI, i.e. cytochrome c maturation system I, an apocytochrome c chaperone, is important and essential for maturation of c-type cytochromes with the non-canonical heme binding motif (HBM) CX2CK, presumably by ensuring that heme attachment at canonical HBMs occurs before apoprotein degradation. Both CcmISo-1 and CcmISo-2 are required for maturation of NrfA. The periplasmic portion of CcmI, CcmI-2, interacts with C-terminus of enzyme NrfA. Heme attachment to the apoprotein is achieved stereochemically by linking of the 2-vinyl and 4-vinyl of heme b via thioether bonds to the N-terminal and C-terminal cysteines, respectively, within heme binding motif. NrfASo is unstable unless heme attachment is timely accomplished, the failure of heme ligation in NrfASo results in rapid degradation, NrfA is rapidly degraded unless properly maturated Shewanella oneidensis

General Information

General Information Comment Organism
physiological function gene SO0265 encodes CcmI, an apocytochrome c chaperone, that is important and essential for maturation of c-type cytochromes with the canonical heme binding motif(s) (HBM and CX2CH) and nitrite reductase NrfA carrying a non-canonical CX2CK motif, respectively. The N-terminal transmembrane segment of CcmI, CcmI-1, is sufficient for maturation of the former but the entire protein is required for maturation of the latter. SirE is not required for maturation of NrfA Shewanella oneidensis