Alteration of transfer ribonucleic acid of Neisseria meningitidis during growth in the presence of human transferrin

Summary. Iron-related tRNA alterations have been shown to occur in several pathogens but nothing has been reported about the effect of iron on meningococcal tRNA. The chromatographic elution profile of 3H-tryptophan-tRNAtrp from a Neisseria meningitidis strain grown under different conditions was examined. The profile showed an early (P1) and a late (P2) eluting species of tRNAtrp, but the proportion of the two species varied under different growth conditions. The elution profile of trp-tRNAtrp from bacteria grown in iron-sufficient Mueller Hinton broth yielded a minor P1 species and a major P2 species, whereas under iron-restricted growth induced by desferrioxamine, the pattern was one of a major P1 species and minor P2 species. Iron-restriction induced by human transferrin (HTF) resulted in almost equal amounts of the two tRNAtrp species (P1 ≏ P2). Differences in the proportions of the tRNA species were also found between cells grown in liquid medium (P1 < P2) and on the same medium solidified with agar (P1 > P2). The growth phase of the bacteria did not have any effect on the tRNAtrp elution profile. Changes in tRNAtrp induced by HTF were readily and completely reversible when the cells were transferred to an iron-rich medium, but those induced by desferrioxamine remained irreversible for a long period (16 h) after such transfer.