title: Characterization of staphyloferrin A biosynthetic and transport mutants in Staphylococcus aureus.
abstract: Iron is critical for virtually all forms of life. The production of high-affinity iron chelators, siderophores, and the subsequent uptake of iron-siderophore complexes are a common strategy employed by microorganisms to acquire iron. Staphylococcus aureus produces siderophores but genetic information underlying their synthesis and transport is limited. Previous work implicated the sbn operon in siderophore synthesis and the sirABC operon in uptake. Here we characterize a second siderophore biosynthetic locus in S. aureus; the locus consists of four genes (in strain Newman these open reading frames are designated NWMN_2079-2082) which, together, are responsible for the synthesis and export of staphyloferrin A, a polycarboxylate siderophore. While deletion of the NWMN_2079-2082 locus did not affect iron-restricted growth of S. aureus, strains bearing combined sbn and NWMN_2079-2082 locus deletions produced no detectable siderophore and demonstrated severely attenuated iron-restricted growth. Adjacent to NWMN_2079-2082 resides the htsABC operon, encoding an ABC transporter previously implicated in haem acquisition. We provide evidence here that HtsABC, along with the FhuC ATPase, is required for the uptake of staphyloferrin A. The crystal structure of apo-HtsA was determined and identified a large positively charged region in the substrate-binding pocket, in agreement with a role in binding of anionic staphyloferrin A.
authors.affiliation: Department of Microbiology and Immunology, University of Western Ontario, London, ON, Canada N6A 5C1.
authors.forename: Federico C
authors.initials: FC
authors.lastname: Beasley
authors.forename: Enrique D
authors.initials: ED
authors.lastname: Vinés
authors.forename: Jason C
authors.initials: JC
authors.lastname: Grigg
authors.forename: Qin
authors.initials: Q
authors.lastname: Zheng
authors.forename: Suya
authors.initials: S
authors.lastname: Liu
authors.forename: Gilles A
authors.initials: GA
authors.lastname: Lajoie
authors.forename: Michael E P
authors.initials: ME
authors.lastname: Murphy
authors.forename: David E
authors.initials: DE
authors.lastname: Heinrichs
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002951:Citrates / Q000096:biosynthesis*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007501:Iron / Q000378:metabolism; D016366:Open Reading Frames; D009876:Operon; D009952:Ornithine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D017262:Siderophores / Q000235:genetics / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002951:Citrates; D017262:Siderophores; C063851:staphyloferrin A; D007501:Iron; D009952:Ornithine