RESULTS:
1 - 3 of 3 for ""enterobactin""
Stenotrophomonas maltophilia produces an EntC-dependent catecholate siderophore that is distinct from enterobactin
Stenotrophomonas maltophilia a Gram-negative multi-drug-resistant bacterium is increasingly recognized as a key opportunistic pathogen. Thus we embarked upon an investigation of S. maltophilia iron acquisition. To begin we determined that the genome of strain K279a is predicted to encode a complete siderophore system including a biosynthesis pathway an outer-membrane receptor for ferrisiderophore and other import and export machinery. Compatible with these data K279a and other clinical isolates of S. maltophilia secreted a siderophore-like activity when grown at 25–37 °C in low-iron media as demonstrated by a chrome azurol S assay which detects iron chelation and Arnow and Rioux assays which detect catecholate structures. Importantly these supernatants rescued the growth of iron-starved S. maltophilia documenting the presence of a biologically active siderophore. A mutation in one of the predicted biosynthesis genes (entC) abolished production of the siderophore and impaired bacterial growth in low-iron conditions. Inactivation of the putative receptor gene (fepA) prevented the utilization of siderophore-containing supernatants for growth in low-iron conditions. Although the biosynthesis and import loci showed some similarity to those of enterobactin a well-known catecholate made by enteric bacteria the siderophore of K279a was unable to rescue the growth of an enterobactin-utilizing indicator strain and conversely iron-starved S. maltophilia could not use purified enterobactin. Furthermore the S. maltophilia siderophore displayed patterns of solubility in organic compounds and mobility upon thin-layer chromatography that were distinct from those of enterobactin and its derivative salmochelin. Together these data demonstrate that S. maltophilia secretes a novel catecholate siderophore.
Idification and structural characterisation of a catecholate-type siderophore produced by Stenotrophomonas maltophilia K279a
Siderophores are produced by several bacteria that utilise iron in various environments. Elucidating the structure of a specific siderophore may have valuable applications in drug development. Stenotrophomonas maltophilia a Gram-negative bacterium that inhabits a wide range of environments and can cause pneumonia produces siderophores. However the structure was unknown and therefore in this study we aimed to elucidate it. We purified siderophores from cultures of S. maltophilia K279a using preparative reversed-phase HPLC. The structure was analysed through LC-MS and 1H and 13C NMR. The results demonstrated that S. maltophilia K279a produces 23-dihydroxybenzoylserine (DHBS) a monomer unit of enterobactin. We suggested the uptake of Iron(III) by the DHBS complex. DHBS production by S. maltophilia K279a could be attributed to an incomplete enterobactin pathway. Drugs targeting DHBS synthesis could prevent S. maltophilia infection.
Siderophore piracy enhances Vibrio cholerae environmental survival and pathogenesis
Vibrio cholerae the aetiological agent of cholera possesses multiple iron acquisition systems including those for the transport of siderophores. How these systems benefit V. cholerae in low-iron polymicrobial communities in environmental settings or during infection remains poorly understood. Here we demonstrate that in iron-limiting conditions co-culture of V. cholerae with a number of individual siderophore-producing microbes significantly promoted V. cholerae growth in vitro. We further show that in the host environment with low iron V. cholerae colonizes better in adult mice in the presence of the siderophore-producing commensal Escherichia coli . Taken together our results suggest that in aquatic reservoirs or during infection V. cholerae may overcome environmental and host iron restriction by hijacking siderophores from other microbes.