Peptide uptake by Salmonella typhimurium. The periplasmic oligopeptide-binding protein.

The uptake of most peptides, including many peptide antibiotics, by the oligopeptide permeases of Escherichia coli and Salmonella typhimurium requires the function of a specific peptide-binding protein (the OppA protein) located within the periplasm. The OppA protein is the largest and most abundant periplasmic substrate-binding protein known and has an unusually broad substrate-binding specificity. The OppA protein has been purified to homogeneity and anti-OppA antibodies have been raised. The sequence of the OppA protein has been deduced from the nucleotide sequence of the oppA gene. This protein is unrelated to any other known periplasmic substrate-binding protein, either immunologically or in its amino acid sequence. The role of this protein in peptide transport is discussed.