Deletions in hydrophilic domains of subunit a from the Escherichia coli F1F0-ATP synthase interfere with membrane insertion or F0 assembly.
The a subunit is a membrane component of the F1F0-ATP synthase from Escherichia coli. Regions of a which appear important for membrane insertion or F0 assembly have been identified by analysis of both deletion mutants and fusion proteins which link the mutant a subunits to alkaline phosphatase. This analysis suggests the hydrophilic, amino-terminal domain of a is required for proper membrane targeting and/or insertion of the nascent polypeptide. In addition, the subcellular fractionation of four different a subunit-beta-galactosidase fusion proteins suggests this domain is localized to the periplasm, in agreement with a proposed topological model of the protein (Lewis, M.J., Chang, J.A., and Simoni, R.D. (1990) J. Biol. Chem. 265, 10541-10550). Deletions within the next three putative loops of a appear to have no significant effect on membrane targeting or insertion. Rather, they seem to interfere with the subsequent assembly of a functional enzyme.
Lewis
M J
MJ
Department of Biological Sciences, Stanford University, California 94305.
Simoni
R D
RD
D000255:Adenosine Triphosphate / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000201:enzymology; D002872:Chromosome Deletion; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D005798:Genes, Bacterial; D005838:Genotype; D046911:Macromolecular Substances; D008961:Models, Structural; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D010957:Plasmids; D011487:Protein Conformation; D006180:Proton-Translocating ATPases / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D046911:Macromolecular Substances; D011993:Recombinant Fusion Proteins; D009243:NAD; D000255:Adenosine Triphosphate; D000469:Alkaline Phosphatase; D001616:beta-Galactosidase; D006180:Proton-Translocating ATPases