A Vertebrate-type Ferredoxin Domain in the Na+-translocating NADH Dehydrogenase fromVibrio cholerae
Journal of Biological Chemistry
The Na ؉ -translocating NADH:quinone oxidoreductase from Vibrio cholerae contains a single Fe-S cluster localized in subunit NqrF. Here we study the electronic properties of the Fe-S center in a truncated version of the NqrF subunit comprising only its ferredoxin-like Fe-S domain. Mö ssbauer spectroscopy of the Fe-S domain in the oxidized state is consistent with a binuclear Fe-S cluster with tetrahedral sulfur coordination by the cysteine residues Cys 70 , Cys 76 , Cys 79 , and Cys 111 .
... and Cys 111 . Important sequence motifs surrounding these cysteines are conserved in the Fe-S domain and in vertebrate-type ferredoxins. The magnetic circular dichroism spectra of the photochemically reduced Fe-S domain exhibit a striking similarity to the magnetic circular dichroism spectra of vertebrate-type ferredoxins required for the in vivo assembly of iron-sulfur clusters. This study reveals a novel function for vertebrate-type [2Fe-2S] clusters as redox cofactors in respiratory dehydrogenases.