InterPro

Bacterial high affinity transport systems are involved in active transport of solutes across the cytoplasmic membrane. Most of the bacterial ABC (ATP-binding cassette) importers are composed of one or two transmembrane permease proteins, one or two nucleotide-binding proteins and a highly specific periplasmic solute-binding protein. In Gram-negative bacteria the solute-binding proteins are dissolved in the periplasm, while in archaea and Gram-positive bacteria, their solute-binding proteins are membrane-anchored lipoproteins [PMID: 8003968, PMID: 18310026].

On the basis of sequence similarities, the vast majority of these solute-binding proteins can be grouped [PMID: 8336670] into eight families or clusters, which generally correlate with the nature of the solute bound. This entry represents a conserved site found in the extracellular solute-binding protein family 5 members from Gram-positive bacteria, Gram-negative bacteria and archaea.

Family 5 members include:

• Periplasmic oligopeptide-binding proteins (gene oppA) of Gram-negative bacteria and homologous lipoproteins in Gram-positive bacteria (genes oppA, amiA or appA).
• Periplasmic dipeptide-binding proteins of Escherichia coli (gene dppA) and of Bacillus subtilis (gene dppE).
• Periplasmic murein peptide-binding protein of E. coli (gene mppA).
• Periplasmic peptide-binding proteins sapA of E. coli, Salmonella typhimurium and Haemophilus influenzae.
• Periplasmic nickel-binding protein (gene nikA) of Escherichia coli.
• Heme-binding lipoprotein (gene hbpA or dppA) from H. influenzae.
• Lipoprotein xP55 from Streptomyces lividans.
• H. influenzae hypothetical protein HI0213.
• Hypothetical protein y4tO from Rhizobium sp. strain NGR234 symbiotic plasmid.
• Hypothetical protein y4wM from Rhizobium strain NGR234 symbiotic plasmid.