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. |
| |
| Authors: | G B Cox D Webb J Godovac-Zimmermann H Rosenberg |
| |
| Affiliation: | Department of Biochemistry, John Curtin School of Medical Research, Australian National University, Canberra City. |
| |
| 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. |
| |
| Keywords: | |
|
|
