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1.8.99.5: dissimilatory sulfite reductase

This is an abbreviated version!
For detailed information about dissimilatory sulfite reductase, go to the full flat file.

Word Map on EC 1.8.99.5

Reaction

a [DsrC protein]-S-sulfanyl-L-cysteine
+ 2 acceptor + 3 H2O =
sulfite
 +
a [DsrC protein]-dithiol
 + 2 reduced acceptor + 2 H+

Synonyms

CNL05500, dSiR, DsrA, DsrAB, DsrC, DsvA, DsvB, hydrogen-sulfide:(acceptor) oxidoreductase, MET5, octahaemcytochrome c MccA, PAE2566, SiRA, siroheme sulfite reductase, sulfite reductase

ECTree

     1 Oxidoreductases
         1.8 Acting on a sulfur group of donors
             1.8.99 With unknown physiological acceptors
                1.8.99.5 dissimilatory sulfite reductase

Cofactor

Cofactor on EC 1.8.99.5 - dissimilatory sulfite reductase

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COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
cytochrome c
octaheme cytochrome
heme
octaheme cytochrome, a homotrimer with an unprecedented fold and heme arrangement, as well as a heme bound to a CX15CH motif. The heterobimetallic active-site heme 2 has a Cu(I) ion juxtaposed to a heme c at a Fe-Cu distance of 4.4 A, active-site heme 2 is bound to a canonical CXXCH motif with H306 as a proximal axial ligand. In the CX15CH motif of heme 8, the extended region between the two cysteine residues forms a loop with a short helical turn, in direct vicinity to another loop harbouring the only non-proline cis peptide in the enzyme, between residues G508 and F509. Its formation might require the essential peptidyl isomerase MccB2, and it is presumed to be a prerequisite for correct folding of the loop in the maturation process of heme 8, which is likely to be attached by the dedicated cytochrome c synthase CcsA1. The structure of the CX15CH heme c binding motif disrupts the general parallel/perpendicular heme stacking sequence, and rotates the heme out of plane, possibly to optimize the interaction with the putative electron donor, the iron-sulfur protein MccC
siroheme
[4Fe-4S]-center
additional information
-
no activity is observed with NAD, NADP, FAD or FMN
-