Loss of transferrin receptor activity in Neisseria meningitidis correlates with inability to use transferrin as an iron source.

AUTOR(ES)

Tsai, J

RESUMO

Although Neisseria meningitidis does not produce siderophores, it is able to obtain iron from human transferrin. We observed saturable specific binding of 125I-labeled human transferrin to meningococci. Human lactoferrin and mouse transferrin did not compete with human transferrin for binding, whereas human apotransferrin and 100% iron-saturated transferrin competed equally well. Meningococci thus have a specific receptor for human transferrin. Scatchard analysis yielded a relatively low Kd of 0.7 microM and an apparent copy number of 2,900 receptors per CFU. Receptor activity was iron-regulated. A meningococcal transformant specifically unable to utilize transferrin as an iron source had decreased transferrin receptor activity. These data are consistent with the hypothesis that receptor-mediated binding of transferrin is a rate-limiting step in meningococcal iron uptake from transferrin.

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