Bacterial extracellular solute-binding protein (IPR006059)

Short name: SBP

Overlapping homologous superfamilies


Family relationships


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 into eight family clusters [PMID: 8336670], which generally correlate with the nature of the solute bound. This entry represents the family 1.

Family 1 members include:

  • Maltose/maltodextrin-binding proteins of Enterobacteriaceae (gene malE) [PMID: 7853407] and Streptococcus pneumoniae malX
  • Multiple oligosaccharide binding protein of Streptococcus mutans (gene msmE)
  • Escherichia coli glycerol-3-phosphate-binding protein
  • Serratia marcescens iron-binding protein (gene sfuA) and the homologous proteins (gene fbp) from Haemophilus influenzae and Neisseria
  • E. coli thiamine-binding protein (gene tbpA)

Interestingly, these thiamin-binding proteins share protein structural similarity with thiaminase-I. They may be evolved from a common ancestor [PMID: 18177053]. This entry also includes thiaminase-1 from Paenibacillus thiaminolyticus (Bacillus thiaminolyticus).

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.