The dyad of the Y-junction- and a flavin module unites diverse redox enzymes

The concomitant presence of two distinctive polypeptide modules, which we have chosen to denominate as the “Y-junction” and “flavin” module, is observed in 3D structures enzymes functionally diverse complex I, NAD(P)-dependent [NiFe]-hydrogenases formate dehydrogenases. Amino acid sequence conservation furthermore suggests that both modules are also part [FeFe]-hydrogenases for no structure model available yet. flavin module harbours site interaction with substrate NAD(P) exchanges electrons a strictly conserved moiety. Y-junction typically contains four iron-sulphur centres arranged form Y-shaped electron transfer conduit mediates between catalytic units respective enzymes. represents an hub three potential entry/exit sites. pattern specific redox present correlated knowledge these enzymes' functional properties. We searched publicly accessible genomes gene clusters containing assemble comprehensive picture diversity harbouring this dyad reconstruct their phylogenetic relationships. These analyses indicate already last universal common ancestor emergence I's EFG-module out subgroup NAD(P)- dependent • A protein confers NAD(P)-dependence otherwise unrelated “flavin module” accomplishes interfacing 2- 1-electron reactions. “Y-junction permits branched transfer. likely makes energy converting bifurcation possible. Phylogenetic inform on evolution I EFG-module.