Homologous Superfamily

TonB-dependent receptor-like, beta-barrel domain superfamily (IPR036942)

Short name: TonB_rcpt_b-brl_sf

Overlapping entries


In Escherichia coli the TonB protein interacts with outer membrane receptor proteins that carry out high-affinity binding and energy-dependent uptake of specific substrates into the periplasmic space [PMID: 14499604]. These substrates are either poorly permeable through the porin channels or are encountered at very low concentrations. In the absence of TonB, these receptors bind their substrates but do not carry out active transport. TonB-dependent regulatory systems consist of six components: a specialised outer membrane-localised TonB-dependent receptor (TonB-dependent transducer) that interacts with its energising TonB-ExbBD protein complex, a cytoplasmic membrane-localised anti-sigma factor and an extracytoplasmic function (ECF)-subfamily sigma factor [PMID: 15993072]. The TonB complex senses signals from outside the bacterial cell and transmits them via two membranes into the cytoplasm, leading to transcriptional activation of target genes. The proteins that are currently known or presumed to interact with TonB include BtuB [PMID: 12652322], CirA, FatA, FcuT, FecA [PMID: 11872840], FhuA [PMID: 9865695], FhuE, FepA [PMID: 9886293], FptA, HemR, IrgA, IutA, PfeA, PupA and Tbp1. The TonB protein also interacts with some colicins. Most of these proteins contain a short conserved region at their N terminus [PMID: 12957833].

This entry covers the conserved part of the beta-barrel domain structure at the C terminus. This beta-barrel domain is also found in vitamin B12 transporter BtuB [PMID: 17548346] and ferric citrate outer membrane transporter FecA [PMID: 11872840] among others.

Contributing signatures

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