Iron and pH-responsive FtrABCD ferrous iron utilization system ofBordetellaspecies

摘要: A putative operon encoding an uncharacterized ferrous iron transport (FtrABCD) system was previously identified in cDNA microarray studies. In growth studies using buffered medium at pH values ranging from pH 6.0 to 7.6, Bordetella pertussis and bronchiseptica FtrABCD mutants showed dramatic reductions yields under iron-restricted conditions pH 6.0, but had no defects pH 7.6. Supplementation of culture with 2 mM ascorbate reductant inhibitory alcaligin siderophore-dependent pH 7.6, a neglible effect on system-dependent assimilation consistent its predicted specificity for iron. Unlike haem systems, agreement hypothesized role inorganic periplasm cytoplasm, function did not require the TonB energy transduction complex. Gene fusion analysis revealed that ftrABCD promoter activity maximal acidic pH. The human airway surface fluids ranges pH 5.5 7.9, may supply necessary host microenvironments which siderophores are ineffective retrieval.