Evidence for siderophore-dependent iron acquisition in group B streptococcus.

摘要: Summary Mutagenesis of group B streptococcus (GBS) with TnphoZ, a transposon designed to identify secreted protein genes, identified the gene homologues fhuD and fhuG. The encoded proteins participate in siderophore (hydroxamate)-dependent iron(III) transport other bacterial species. Sequence analysis genome determined that fhuG are members polycistronic operon comprised four fhuCDBG, encode putative ATPase, cell surface receptor two transmembrane respectively. We hypothesized FhuD was receptor. Western extracts localized membrane. Fluorescence quenching experiments purified bound hydroxamate-type siderophores. displayed highest affinity for iron(III)-desferroxamine, KD (µM) = 0.05, identical described FhuD2 from Staphylococcus aureus. role Fhu siderophore-iron also characterized. A fhu mutant, ACFhu1, equally sensitive iron-dependent antibiotic streptonigrin as wild-type strain, suggesting ACFhu1 not reduced intracellular iron concentrations absence exogenous siderophore. However, transported significantly less siderophore-bound 55Fe accumulation assays. These data provide first evidence siderophore-mediated acquisition by GBS.