S. aureus exoproteome in the context of genetic competence development

To perform natural transformation, one of the three main Horizontal Gene Transfer mechanisms, bacteria need to enter a physiological differentiated state called genetic competence. Interestingly, new bacteria displaying such aptitude are often discovered, and one of the latest is the human pathogen Staphylococcus aureus. Here, we developed a new protocol, based on planktonic cells cultures, leading to a large percentage of the population activating competence development and a significant improvement of S. aureus natural transformation efficiencies. Taking advantage of these new conditions, we performed transcriptomics analyses to characterize each central competence regulators regulon. SigH and ComK1 were both found essential for activating natural transformation genes but also important for activation or repression of peripheral functions. Even though ComK2 was not found important for the control of transformation genes, its regulon showed an important overlap with that of SigH and ComK1. Finally, we showed how microaerobic conditions, sensed by the SrrAB two-component system, was key to activate competence in S. aureus.