title: Identification and characterization of the Staphylococcus aureus gene cluster coding for staphyloferrin A.
abstract: Siderophores are key virulence factors that allow bacteria to grow in iron-restricted environments. The Gram-positive pathogen Staphylococcus aureus is known to produce four siderophores for which genetic and/or structural data are unknown. Here we characterize the gene cluster responsible for producing the prevalent siderophore staphyloferrin A. In addition to expressing the cluster in the heterologous host Escherichia coli, which confers the ability to synthesize the siderophore, we reconstituted staphyloferrin A biosynthesis in vitro by expressing and purifying two key enzymes in the pathway. As with other polycarboxylate siderophores, staphyloferrin A is biosynthesized using the recently described nonribosomal peptide synthetase independent siderophore (NIS) biosynthetic pathway. Two NIS synthetases condense two molecules of citric acid to d-ornithine in a stepwise ordered process with SfnaD using the delta-amine as a nucleophile to form the first amide followed by SfnaB utilizing the alpha-amine to complete staphyloferrin A synthesis.
authors.affiliation: Department of Infectious Diseases, Novartis Institutes for BioMedical Research, 500 Technology Square, Cambridge, Massachusetts 02139, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Cotton
authors.forename: Jianshi
authors.initials: J
authors.lastname: Tao
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Balibar
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D002951:Citrates / Q000737:chemistry; D019295:Computational Biology / Q000379:methods; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005815:Genetic Code; D005810:Multigene Family; D009952:Ornithine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000235:genetics; D010453:Peptide Synthases / Q000737:chemistry / Q000235:genetics*; D017262:Siderophores / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D013211:Staphylococcus aureus / Q000737:chemistry / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D002951:Citrates; D017262:Siderophores; C063851:staphyloferrin A; D009952:Ornithine; D010453:Peptide Synthases; C104385:non-ribosomal peptide synthase