Expression of a high-affinity mechanism for acquisition of transferrin iron by Neisseria meningitidis

Abstract

Fe-starved meningococci grown at either pH 7.2 or 6.6 were capable of removing and incorporating Fe from human transferrin by a saturable, cell surface mechanism that specifically recognized transferrin rather than Fe. The maximum expression of the Fe uptake system occurred after 4 h of Fe starvation. The uptake of the Fe was dependent upon a functioning electron transport chain and was sensitive to 60.degree. C and trypsin. Cells grown under Fe sufficient conditions were incapable of accumulating Fe from transferrin. No evidence was found for a primary role for cell-free soluble siderophores in the removal of Fe from transferrin. The nonpathogenic neisseriae, N. flava and N. sicca, were unable to utilize Fe on transferrin.