FhuD: Difference between revisions

<applet load='1esz' size='400' frame='true' align='right' caption='Strucutre of the Periplasmic Ferric Siderophore Binding Protein FhuD complexed with the siderophore coprogen as determined by Clarke et al. [[1esz]]' />

Siderophore-binding proteins can be found in both Gram-positive and Gram-negative bacteria in divisions: hydroxamates, catecholates, and carboxylates.<ref name="lu">PMID: 11805094</ref>  In Escherichia coli. (E. coli) the ATP-binding cassette- type (ABC-type) protein '''FhuD''' (part of the helical backbone metal receptor superfamily) is a common periplasmic protein which facilitates the transport of a variety of hydoxamate siderophores to the inner membrane-associated proteins FhuB and FhuC.<ref name="lu"/> The structure of FhuD is atypical for periplasmic ligand binding protein due to its bilobal mixture of two α/β domains connected by long α-helix.<ref name="lu"/>,<ref name="la">PMID: 10742172</ref>

Unlike other periplasmic ligand binding protein (PLBP), FhuD does not have the characteristic fold of a bilobate domain connected by flexible β-strands at the base of the ligand binding pocket.<ref name="lu"/> This results in FhuD adopting a novel PLBP structure.<ref name="lu"/> As designated by its structure, FhuD binds hydroxamate siderophores into a primarily hydrophobic pocket allowing the assumption that both binding and release do not cause large scale opening/closing.<ref name="la"/> However in the binding pocket, several major ligand binding side chains have been noted in various positions depending on the ligand bound.<ref name="lu"/>,<ref name="la"/> Due to the ability of siderophore binding uptake systems to allow such a diverse array of siderophore bound molecules, new bacterial growth inhibiting agents may be developed.<ref name="lu"/> These agents will be delivered into the bacteria as silent “Trojan Horses” by the bacteria’s own uptake system.<ref name="lu"/>