title: Arg-220 of the PstA protein is required for phosphate transport through the phosphate-specific transport system in Escherichia coli but not for alkaline phosphatase repression.
abstract: The pstA gene encodes an integral membrane protein of the phosphate-specific transport system of Escherichia coli. The nucleotide change in the previously described pstA2 allele was found to be a G----A substitution at position 276 of the nucleotide sequence, resulting in the premature termination of translation. Three mutations in the pstA gene were produced by site-directed mutagenesis. The amino acid substitutions resulting from the three site-directed mutations were Arg-170----Gln, Glu-173----Gln, and Arg-220----Gln. These amino acid residues were selected because a previous PstA protein structure prediction placed them within the membrane. The Arg-220----Gln mutation resulted in the loss of phosphate transport through the phosphate-specific transport system, but the alkaline phosphatase activity remained repressed. Neither the Arg-170----Gln nor the Glu-173----Gln mutation affected phosphate transport. The results are discussed in relation to a proposed structure of the PstA protein.
mesh_terms: D000469:Alkaline Phosphatase / Q000096:biosynthesis*; D000483:Alleles; D001120:Arginine / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004794:Enzyme Repression; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D005973:Glutamine / Q000378:metabolism; D009154:Mutation; D028044:Phosphate-Binding Proteins; D010710:Phosphates / Q000378:metabolism*; D014176:Protein Biosynthesis
chemical_list: D002352:Carrier Proteins; D005971:Glutamates; D028044:Phosphate-Binding Proteins; D010710:Phosphates; D005973:Glutamine; D018698:Glutamic Acid; D001120:Arginine; D000469:Alkaline Phosphatase