Competence development by Haemophilus influenzae is regulated by the availability of nucleic acid precursors.

摘要: DNA uptake by naturally competent bacteria provides cells with both genetic information and nucleotides. In Haemophilus influenzae, competence development requires cAMP an unidentified signal arising under starvation conditions. To investigate this signal, induction was examined in media supplemented nucleic acid precursors. The addition of physiological levels AMP GMP reduced 200-fold prevented the normal competence-induced transcription essential genes comA rec-2. rich medium normally used for growth allows only limited competence. Capillary electrophoresis revealed a subinhibitory amount no detectable GMP, or to also 20- 100-fold. Neither functional stringent response system nor phosphoenolpyruvate:glycose phosphotransferase (PTS) found be required purine-mediated repression. Added partially restored development, suggesting that purines may reduce cAMP. Potential binding sites PurR repressor were identified several genes, is part PUR regulon. These observations are consistent models regulation, which depleted purine pools need nucleotides, support hypothesis evolved primarily nucleotide acquisition.