Difference between revisions of "Part:BBa K2273012"

This promoter is part of the well-studied regulatory system for competence development in Bacillus subtilis (Figure 1). B. subtilis constantly secretes the ComX pheromone (BBa_K2273003), a 9- to 10-amino acid oligopeptide, as a signalling molecule (a). By rising cell-density, the ComX-concentration in the surrounding medium increases until it reaches a threshold and activates ComP, a membrane-spanning protein kinase (b). This mechanism is called quorum sensing. The kinase reacts to the accumulation of ComX by phosphorylating the response regulator ComA (c) which then works as a transcription factor by binding to several promoters and enhancing their activity (d). (Hamoen et al.)
The most important promoter regulated by ComA and involved in competence development is the promoter of the srfA operon (P_srfA, BBa_K2273000). This operon contains not only genes for the production of the antibiotic surfactin (e) but also for ComS (f), another small peptide that prevents the degradation of the autoregulated transcription factor ComK (g). ComK activates expression of more than 100 genes, including comG, that is part of the transformation machinery (h) (Comella et al.,Susanna et al.). Consequently, B. subtilis can take up DNA from the environment either as direct nutrient source or incorporate the DNA via homologues recombination into its own genome.
Since the competence development is not only dependent on quorum sensing but also on nutritional conditions, we evaluated the influence of different media (Figure 2). We tested full medium (LB) as well as minimal media (MNGE, MCSE).