title: Two nuclear-coded subunits of mitochondrial complex I are similar to different domains of a bacterial formate hydrogenlyase subunit.
abstract: A computer comparison of protein sequences revealed similarity between the 30.4 kDa subunit of complex I from the fungus Neurospora crassa and the ORF5 subunit of formate hydrogenlyase from Escherichia coli. The ORF5 protein was previously known to be homologous to the 49 kDa component of the mitochondrial enzyme. We show that the 30.4 kDa corresponds to the N-terminal part while the 49 kDa subunit corresponds to the C-terminal portion of the bacterial protein. Thus, this bacterial protein represents a fusion of the two mitochondrial polypeptides suggesting that the two complex I genes arose from a single ancestor. Our results indicate that the 30.4 kDa and 49 kDa subunits are part of a structural and functional unit in complex I.
authors.affiliation: Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Portugal.
authors.forename: A
authors.initials: A
authors.lastname: Videira
authors.forename: J E
authors.initials: JE
authors.lastname: Azevedo
mesh_terms: D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000201:enzymology*; D004926:Escherichia coli / Q000201:enzymology*; D005560:Formate Dehydrogenases / Q000737:chemistry*; D006864:Hydrogenase / Q000737:chemistry*; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry*; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
chemical_list: D009097:Multienzyme Complexes; D006864:Hydrogenase; D005560:Formate Dehydrogenases; C054017:formate hydrogenlyase; D016660:NAD(P)H Dehydrogenase (Quinone)