The availability of purine nucleotides regulates natural competence by controlling translation of the competence activator Sxy
Article first published online: 13 MAY 2013
© 2013 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Volume 88, Issue 6, pages 1106–1119, June 2013
How to Cite
Sinha, S., Mell, J. and Redfield, R. (2013), The availability of purine nucleotides regulates natural competence by controlling translation of the competence activator Sxy. Molecular Microbiology, 88: 1106–1119. doi: 10.1111/mmi.12245
- Issue published online: 10 JUN 2013
- Article first published online: 13 MAY 2013
- Manuscript Accepted: 23 APR 2013
- Canadian Institutes for Health Research
Many bacteria are naturally competent, able to bind and take up DNA from their extracellular environment. This DNA can serve as a significant source of nutrients, in addition to providing genetic material for recombination. The regulation of competence in several model organisms highlights the importance of this nutritional function, although it has often been overlooked. Natural competence is induced by starvation in Haemophilus influenzae, the model for competence regulation in the gamma-proteobacteria. This induction depends on the activation of the global metabolic regulator CRP, which occurs upon depletion of phosphotransferase sugars. In this work, we show that the depletion of purine nucleotides under competence-inducing conditions activates the CRP-dependent competence-specific regulator Sxy. Depletion of extra- or intra-cellular purine nucleotides activates Sxy translation, while high levels inhibit it. This is modulated by the stem structure formed by sxy mRNA. The exact mechanism by which the nucleotide depletion signal is transduced is unclear, but it does not involve direct binding of purine intermediates to the sxy stem, and does not require Hfq or competence proteins. Similar regulation occurs in the relatives of H. influenzae, Actinobacillus pneumoniae and A. suis, confirming the importance of processes enabling competent bacteria to exploit the abundant DNA in their environments.