{PDOC00354} {PS00430; TONB_DEPENDENT_REC_1} {PS01156; TONB_DEPENDENT_REC_2} {PS52016; TONB_DEPENDENT_REC_3} {BEGIN} ****************************************************************** * TonB-dependent receptor (TBDR) proteins signatures and profile * *************************************************************"**** In addition to a cytoplasmic membrane (CM), which is common to all organisms, Gram-negative bacteria possess an outer membrane (OM) that acts as a selective permeation barrier. TonB-dependent receptors (TBDRs) are transport proteins found at the OM to allow Gram-negative bacteria to uptake scarce resources from competitive environments with very high affinity. Early reports on TBDRs focused on the uptake of siderophore-iron complexes but recent studies have showed that the spectrum of ligands includes sugars, vitamins, heme, and other non-ferrous cations. All of them share the same basic architecture, a C- terminal membrane-embedded 22-strand antiparallel beta-barrel domain that is sealed by a conserved N-terminal globular 'plug' domain (also called 'cork' or 'hatch') (see ). The lengths of the extracellular loops from the plug and barrel domain are the main structural differences between the TBDRs. The extracellular loops are involved in transport. Their flexibility allows for the ligand recognition before binding into its binding pocket. TBDRs typically act as channels that open in response to outside ligands to allow import of extracellular nutrients into the periplasmic space. The TBDR- dependent substrate transport is an active process that requires energy input from the proton motive force across the cytoplasmic membrane. Such a process requires that the ligand-loaded TBDRs interact with the TonB protein complex consisting of three inner membrane proteins (TonB/ExbB/ExbD) (see . ExbB and ExbD are accessory proteins anchored in the CM that convey the pmf across the CM to TonB. TonB protein mediates the energy transduction from the CM to TBDRs [1,2,3,4,5,6,7]. The TonB protein also interacts with some colicins. The proteins that are currently known or presumed to interact with TonB are: Gene Function or name ---- ------------------------------------------------------------------- btuB Receptor for cobalamin. cirA Receptor for colicin I (exact substrate not known). fatA Receptor for ferric anguibactin (Vibrio anguillarum). fcuA Receptor for ferrichrome (Yersinia enterocolitica). fecA Receptor for iron dicitrate. fepA Receptor for ferrienterobactin (ferric enterochelin). fhuA Receptor for ferrichrome-iron. fhuE Receptor for ferric coprogen, ferrioxamine B, and rhodotrulic acid. foxA Receptor for ferrioxamine (Yersinia enterocolitica). fptA Receptor for Fe(III)-pyochelin (Pseudomonas aeruginosa). fpvA Receptor for ferripyoverdine (Pseudomonas aeruginosa). fyuA Receptor for pesticin and yersiniabactin (Yersinia). hemR Receptor for hemin (Yersinia enterocolitica). hxuC Receptor for heme/hemopexin (Haemophilus influenzae). irgA Receptor for ferric vibriobactin (Vibrio cholerae). iroA Receptor for a siderophore (Neisseria meningitidis). iutA Receptor for ferric aerobactin. pbuA Receptor for ferric pseudobactin M114 (Pseudomonas strain M114). pfeA Receptor for ferric enterobactin (Pseudomonas aeruginosa). pupA Receptor for ferric pseudobactin 358 (Pseudomonas putida). pupB Receptor for ferric pseudobactin BN7 and BN8 (Pseudomonas putida). tbp1 Receptor for transferrin (Neisseria and Haemophilus). Haemophilus influenzae hypothetical proteins HI0262, HI0661, HI0635, HI0712, HI1217, and HI1567. cba Colicin B, a channel forming colicin. cda Colicin D. cma Colicin M, inhibitor of murein biosynthesis. Most of these proteins contain, at their N-terminus, a short conserved region [8,9,10], called the TonB-box, involved in the interaction of the protein with the TonB protein [11]. With the exception of the colicin B, D and M receptors they all also contain, in their C-terminal extremity a short conserved domain that contains two invariant residues. We also developed a profile that covers both the N-terminal plug domain and the C-terminal beta-barrel domain. -Consensus pattern: -Sequences known to belong to this class detected by the pattern: ALL, except for hemR and cba/cda/cma. -Other sequence(s) detected in Swiss-Prot: NONE. -Sequences known to belong to this class detected by the profile: ALL. -Other sequence(s) detected in Swiss-Prot: NONE. -Last update: January 2023 / Text revised; profile added. [ 1] Lim B.L. "TonB-dependent receptors in nitrogen-fixing nodulating bacteria." Microbes. Environ. 25:67-74(2010). PubMed=21576856; DOI=10.1264/jsme2.me10102 [ 2] de Amorim G.C., Prochnicka-Chalufour A., Delepelaire P., Lefevre J., Simenel C., Wandersman C., Delepierre M., Izadi-Pruneyre N. "The structure of HasB reveals a new class of TonB protein fold." PLoS One. 8:E58964-E58964(2013). PubMed=23527057; DOI=10.1371/journal.pone.0058964 [ 3] Koedding J., Killig F., Polzer P., Howard S.P., Diederichs K., Welte W. "Crystal structure of a 92-residue C-terminal fragment of TonB from Escherichia coli reveals significant conformational changes compared to structures of smaller TonB fragments." J. Biol. Chem. 280:3022-3028(2005). PubMed=15522863; DOI=10.1074/jbc.M411155200 [ 4] Wang R., Xu H., Du L., Chou S.-H., Liu H., Liu Y., Liu F., Qian G. "A TonB-dependent receptor regulates antifungal HSAF biosynthesis in Lysobacter." Sci. Rep. 6:26881-26881(2016). PubMed=27241275; DOI=10.1038/srep26881 [ 5] Krieg S., Huche F., Diederichs K., Izadi-Pruneyre N., Lecroisey A., Wandersman C., Delepelaire P., Welte W. "Heme uptake across the outer membrane as revealed by crystal structures of the receptor-hemophore complex." Proc. Natl. Acad. Sci. U. S. A. 106:1045-1050(2009). PubMed=19144921; DOI=10.1073/pnas.0809406106 [ 6] Cobessi D., Meksem A., Brillet K. "Structure of the heme/hemoglobin outer membrane receptor ShuA from Shigella dysenteriae: heme binding by an induced fit mechanism." Proteins 78:286-294(2010). PubMed=19731368; DOI=10.1002/prot.22539 [ 7] Oeemig J.S., Ollila O.H.S., Iwai H. "NMR structure of the C-terminal domain of TonB protein from Pseudomonas aeruginosa." PeerJ 6:E5412-E5412(2018). PubMed=30186676; DOI=10.7717/peerj.5412 [ 8] Lundrigan M.D., Kadner R.J. "Nucleotide sequence of the gene for the ferrienterochelin receptor FepA in Escherichia coli. Homology among outer membrane receptors that interact with TonB." J. Biol. Chem. 261:10797-10801(1986). PubMed=3015941 [ 9] Schramm E., Mende J., Braun V., Kamp R.M. "Nucleotide sequence of the colicin B activity gene cba: consensus pentapeptide among TonB-dependent colicins and receptors." J. Bacteriol. 169:3350-3357(1987). PubMed=2439491 [11] Nau C.D., Konisky J. "Evolutionary relationship between the TonB-dependent outer membrane transport proteins: nucleotide and amino acid sequences of the Escherichia coli colicin I receptor gene." J. Bacteriol. 171:1041-1047(1989). PubMed=2644220 [ 4] Gudmundsdottir A., Bell P.E., Lundrigan M.D., Bradbeer C., Kadner R.J. "Point mutations in a conserved region (TonB box) of Escherichia coli outer membrane protein BtuB affect vitamin B12 transport." J. Bacteriol. 171:6526-6533(1989). PubMed=2687240 -------------------------------------------------------------------------------- PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND 4.0) License, see https://prosite.expasy.org/prosite_license.html -------------------------------------------------------------------------------- {END}