| Primary Identifier | IPR007202 | Type | Domain |
| Short Name | 4Fe-4S_dom |
| description | The cobalt- and iron-containing corrinoid iron-sulfur protein (CoFeSP) isfunctional in the acetyl-CoA pathway of autotrophic carbon fixation in variousbacteria and acrchaea, where it is essential for the biosynthesis of acetyl-CoA. CoFeSP acts in two methylation reactions: the transfer of a methyl groupfrom methyltransferase (MeTr)-bound methyltetrahydrofolate to the cob(I)amideof CoFeSP and the transfer of the methyl group of methyl-cob(III)amide to thereduced Ni-Ni-[4Fe-4S]active site cluster A of acetyl-CoA synthase (ACS).CoFeSP is a heterodimer consisting of a large subunit (CfsA) and a smallsubunit (CfsB). The large subunit has three domains: an amino (N)-terminal 4Fe-4S domain, a TIM barrel domain and a carboxy (C)-terminal domain thatbinds CoBeta-aqua-(5,6-dimethylbenzimiddazolylcobamide) (corrinoid).Methylation of CoFeSP only occurs in the low potential Co(I) state, which canbe sporadically oxidized to the inactive Co(II) state, making its reductivereactivation necessary. The low-potential [4Fe-4S]2(+)/1(+) cluster isinvolved in the reductive reactivation of CoFeSP and is able to transferelectrons to cob(II)amide from NiFe-containing carbon monoxyde dehydrogenase(CODH), pyruvate:ferredoxin oxydoreductase or reduced ferredoxins [, , ].The 4Fe-4S domain lacks homology to the 4Fe-4S ferredoxin-type iron-sulfurbinding domain, but is also found in bacterial electrontransport complex protein RnfB [].The 4Fe-4S domain consists of four helices (three α-helices from H1-H3 andone 3(10)-helix with the order alphaH1-alphaH2-3(10)H-alphaH3). This four-helix-bundle-like architecture positions the fourcysteinyl ligands of the [4Fe-4S]cluster. The iron-sulfur cluster bindingmotif Cys-X(2)-Cys-X(4)-Cys-X(16)-Cys is located at loops connecting alphaH1and alphaH2, connecting 3(10)H and alphaH3, and at the end of alphaH2. The[4Fe-4S]cluster is placed near the surface of the 4Fe-4S domain, but isshielded from the solvent by hydrophobic amino acids [, ].This entry represents the 4Fe-4S domain. |
