Identification and characterization of dppA, an Escherichia coli gene encoding a periplasmic dipeptide transport protein.
We describe the isolation and analysis of an Escherichia coli gene, dppA, and its role in dipeptide transport. dppA maps near min 79 and encodes a protein (DppA) that has regions of amino acid similarity with a peptide-binding protein from Salmonella typhimurium (OppA). Like OppA, DppA is found in the periplasmic space and thus is most likely a dipeptide-binding protein. Insertional inactivation of dppA results in the inability of a proline auxotroph to utilize Pro-Gly as a proline source. dppA-dependent Pro-Gly utilization does not require any of the three major proline transport systems, demonstrating that DppA is not simply a dipeptidase. An in vivo competition assay was used to show that DppA is probably involved in the transport of dipeptides other than Pro-Gly. Transcription of dppA is repressed by the presence of casamino acids, suggesting that the cell alters its dipeptide transport capabilities in response to an environmental signal.
Molecular Biology Research, Upjohn Company, Kalamazoo, Michigan 49007.
E R
ER
Olson
D S
DS
Dunyak
L M
LM
Jurss
R A
RA
Poorman
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D010582:Bacteriophage lambda / Q000235:genetics; D001483:Base Sequence; D001692:Biological Transport; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D026901:Membrane Transport Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes; D033902:Periplasmic Binding Proteins; D010957:Plasmids; D012329:RNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D015345:Oligonucleotide Probes; D033902:Periplasmic Binding Proteins; D012329:RNA, Bacterial; C066768:dppA protein, E coli; C037230:oligopeptide permease, Bacteria