title: Revised transmembrane orientation of the NADH:quinone oxidoreductase subunit NuoA.
abstract: NuoA is a small membrane spanning subunit of respiratory chain NADH:quinone oxidoreductase (complex I). Unlike the other complex I core protein subunits, the NuoA protein has no known homologue in other enzyme systems. The transmembrane orientation of NuoA cannot be unambiguously predicted, due to the small size of the polypeptide and the varying distribution of charged amino acid residues in NuoA from different organisms. Novel analyses of NuoA from Escherichia coli complex I expressed as fusion proteins to cytochrome c and to alkaline phosphatase demonstrated that the c-terminal end of the polypeptide is localized in the bacterial cytoplasm, in contrast to what was previously reported for the homologous NQO7 subunit from Paracoccus denitrificans complex I.
authors.affiliation: Department of Biochemistry and Structural Biology, Center for Molecular Protein Science, Lund University, Lund, Sweden.
authors.forename: Egle
authors.initials: E
authors.lastname: Virzintiene
authors.forename: Maria
authors.initials: M
authors.lastname: Trane
authors.forename: Cecilia
authors.initials: C
authors.lastname: Hägerhäll
mesh_terms: D002462:Cell Membrane / Q000201:enzymology* / Q000235:genetics; D042967:Electron Transport Complex I / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010231:Paracoccus denitrificans / Q000201:enzymology / Q000235:genetics; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D040681:Structural Homology, Protein
chemical_list: D029968:Escherichia coli Proteins; D021122:Protein Subunits; D042967:Electron Transport Complex I