|PROSITE documentation PDOC50983 [for PROSITE entry PS50983]|
ATP binding cassette (ABC) transporters are a ubiquitous family of importer and exporter proteins that consist of two α-helical transmembrane (TM) domains, which form a translocation pathway, and two cytoplasmic ABC domains, which power the transport reaction through binding and hydrolysis of ATP (see <PDOC00364>). In addition most bacterial importers employs a periplasmic substrate-binding protein (PBP) that delivers the ligand to the extracellular gate of the TM domains. These proteins bind their substrates selectively and with high affinity, which is thought to ensure the specificity of the transport reaction. Binding proteins in Gram-negative bacteria are present within the periplasm, whereas those in Gram-positive bacteria are tethered to the cell membrane via the acylation of a cysteine residue that is an integral component of a lipoprotein signal sequence. The cobalamin (vitamin B12) and the iron transport systems share many common attributes and probably evolved from the same origin [1,2,3,4].
The structure of the periplasmic-binding domain is composed of two subdomains, each consisting of a central β-sheet and surrounding α-helices, linked by a rigid α-helix (see <PDB:1N4A>). The substrate binding site is located in a cleft between the two α/β subdomains .
Some protein known to contain an iron siderophore/cobalamin periplasmic-binding domain are listed below:
The profile we developed covers the entire iron siderophore/cobalamin periplasmic-binding domain.Last update:
April 2004 / First entry.
PROSITE method (with tools and information) covered by this documentation:
|1||Authors||Borths E.L. Locher K.P. Lee A.T. Rees D.C.|
|Title||The structure of Escherichia coli BtuF and binding to its cognate ATP binding cassette transporter.|
|Source||Proc. Natl. Acad. Sci. U.S.A. 99:16642-16647(2002).|
|2||Authors||Sebulsky M.T. Shilton B.H. Speziali C.D. Heinrichs D.E.|
|Title||The role of FhuD2 in iron(III)-hydroxamate transport in Staphylococcus aureus. Demonstration that FhuD2 binds iron(III)-hydroxamates but with minimal conformational change and implication of mutations on transport.|
|Source||J. Biol. Chem. 278:49890-49900(2003).|
|3||Authors||Staudenmaier H. Van Hove B. Yaraghi Z. Braun V.|
|Title||Nucleotide sequences of the fecBCDE genes and locations of the proteins suggest a periplasmic-binding-protein-dependent transport mechanism for iron(III) dicitrate in Escherichia coli.|
|Source||J. Bacteriol. 171:2626-2633(1989).|
|4||Authors||Koester W.L. Actis L.A. Waldbeser L.S. Tolmasky M.E. Crosa J.H.|
|Source||J. Biol. Chem. 266:23829-23833(1991).|
|5||Authors||Karpowich N.K. Huang H.H. Smith P.C. Hunt J.F.|
|Title||Crystal structures of the BtuF periplasmic-binding protein for vitamin B12 suggest a functionally important reduction in protein mobility upon ligand binding.|
|Source||J. Biol. Chem. 278:8429-8434(2003).|