title: Hydroxamate-mediated transport of iron controlled by ColV plasmids.
abstract: A new high-affinity system for iron transport, associated with the presence of ColV plasmids, has been detected in Escherichia coli and partially characterized. The presence of such "iron-transport plasmids" in E. coli cells that are defective in enterochelin-mediated transport of iron enabled them to grow in media to which 2,2'-dipyridyl had been added to reduce availability of iron. In addition, the presence of plasmid deoxyribonucleic acid in a mutant defective in enterochelin biosynthesis was associated with a marked increase in the rate of radioactive-iron uptake. Plasmid-determined uptake of iron was distinct from previously recognized systems for iron transport in E. coli K-12, and the colicin V molecule appeared not to be directly involved. Hydroxylamine-nitrogen could be detected in cell pellets of ColV+ cultures, and similar material was detected in supernatant fluids of late log- or stationary-phase cultures. The hydroxamate material was not detected in cell pellets or culture supernatants of strains from which plasmids had been eliminated, and a 95% decrease in hydroxamate synthesis was observed when cells were grown in minimal medium containing 2 microM iron.
mesh_terms: D001693:Biological Transport, Active; D003087:Colicins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000032:analysis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D006877:Hydroxamic Acids / Q000032:analysis / Q000096:biosynthesis*; D007501:Iron / Q000378:metabolism*; D010957:Plasmids
chemical_list: D003087:Colicins; D006877:Hydroxamic Acids; D007501:Iron