title: Interactions of the periplasmic binding protein CeuE with Fe(III) n-LICAM4-siderophore analogues of varied linker length.
abstract: Bacteria use siderophores to mediate the transport of essential Fe(III) into the cell. In Campylobacter jejuni the periplasmic binding protein CeuE, an integral part of the Fe(III) transport system, has adapted to bind tetradentate siderophores using a His and a Tyr side chain to complete the Fe(III) coordination. A series of tetradentate siderophore mimics was synthesized in which the length of the linker between the two iron-binding catecholamide units was increased from four carbon atoms (4-LICAM4-) to five, six and eight (5-, 6-, 8-LICAM4-, respectively). Co-crystal structures with CeuE showed that the inter-planar angles between the iron-binding catecholamide units in the 5-, 6- and 8-LICAM4-structures are very similar (111°, 110° and 110°) and allow for an optimum fit into the binding pocket of CeuE, the inter-planar angle in the structure of 4-LICAM4-is significantly smaller (97°) due to restrictions imposed by the shorter linker. Accordingly, the protein-binding affinity was found to be slightly higher for 5- compared to 4-LICAM4-but decreases for 6- and 8-LICAM4-. The optimum linker length of five matches that present in natural siderophores such as enterobactin and azotochelin. Site-directed mutagenesis was used to investigate the relative importance of the Fe(III)-coordinating residues H227 and Y288.
authors.affiliation: Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.|Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
authors.forename: Ellis J
authors.initials: EJ
authors.lastname: Wilde
authors.affiliation: Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
authors.forename: Adam
authors.initials: A
authors.lastname: Hughes
authors.affiliation: Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
authors.forename: Elena V
authors.initials: EV
authors.lastname: Blagova
authors.affiliation: Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Moroz
authors.affiliation: Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
authors.forename: Ross P
authors.initials: RP
authors.lastname: Thomas
authors.affiliation: Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
authors.forename: Johan P
authors.initials: JP
authors.lastname: Turkenburg
authors.affiliation: Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Raines
authors.affiliation: Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
authors.forename: Anne-Kathrin
authors.initials: AK
authors.lastname: Duhme-Klair
authors.affiliation: Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
authors.forename: Keith S
authors.initials: KS
authors.lastname: Wilson
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D016123:Campylobacter jejuni / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D005290:Ferric Compounds / Q000737:chemistry / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D033862:Iron-Binding Proteins; D009154:Mutation; D019897:Periplasm / Q000378:metabolism; D033902:Periplasmic Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017262:Siderophores / Q000737:chemistry / Q000378:metabolism*; D013095:Spermidine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D005290:Ferric Compounds; D033862:Iron-Binding Proteins; D033902:Periplasmic Binding Proteins; D017262:Siderophores; C433864:ceuE protein, Campylobacter jejuni; C030662:N,N',N''-tris(2,3-dihydroxy-5-sulfobenzoyl)-1,5,10-triazadecane; D013095:Spermidine