Abstract
Bacillus subtilis develops genetic competence for the uptake of foreign DNA when cells enter stationary phase and a high cell density is reached. These signals are integrated by the competence transcription factor ComK, which is subject to transcriptional, post-transcriptional and post-translational regulation. Many proteins are involved in the development of competence, both to control ComK activity and to mediate DNA uptake. However, for many proteins, the precise function they play in competence development is unknown. In this study, we assessed whether proteins required for genetic transformation play a role in the activation of ComK or rather act downstream of competence gene expression. While these possibilities could be distinguished for most of the tested factors, we assume that two proteins, PNPase and the transcription factor YtrA, are required both for full ComK activity and for the downstream processes of DNA uptake and integration. Further analyses of the role of the transcription factor YtrA for the competence development revealed that the overexpression of the YtrBCDEF ABC transporter in the ytrA mutant causes the loss of genetic competence. Moreover, overexpression of this ABC transporter also affects biofilm formation. Since the ytrGABCDEF operon is naturally induced by cell wall-targeting antibiotics, we tested the cell wall properties upon overexpression of the ABC transporter and observed an increased thickness of the cell wall. The composition and properties of the cell wall are important for competence development and biofilm formation, suggesting that the observed phenotypes are the result of the increased cell wall thickness as an outcome of YtrBCDEF overexpression.
Highlights
The Gram-positive model bacterium Bacillus subtilis has evolved many different ways to survive harsh environmental conditions, i.e., it can form highly resistant spores, secrete toxins to kill and cannibalize neighboring cells, form resistant macroscopic biofilms or become competent for transformation [reviewed in López and Kolter (2010)].Role of the YtrBCDEF ABC Transporter in Bacillus subtilisDevelopment of genetic competence is a strategy, which allows bacterial cells to take up foreign DNA from the environment in order to increase the genetic variability of the population
We identified the YtrBCDEF ABC transporter, which is encoded in the ytrGABCDEF operon as an important player for B. subtilis differentiation, since its overexpression does result in a complete loss of competence by a so far unknown mechanism, it affects the proper development of other lifestyles of B. subtilis
Genetic work with B. subtilis is facilitated by the development of genetic competence, a process that depends on a large number of factors
Summary
The Gram-positive model bacterium Bacillus subtilis has evolved many different ways to survive harsh environmental conditions, i.e., it can form highly resistant spores, secrete toxins to kill and cannibalize neighboring cells, form resistant macroscopic biofilms or become competent for transformation [reviewed in López and Kolter (2010)].Role of the YtrBCDEF ABC Transporter in Bacillus subtilisDevelopment of genetic competence is a strategy, which allows bacterial cells to take up foreign DNA from the environment in order to increase the genetic variability of the population. Transcription of the comK gene is controlled by three repressor proteins, Rok, CodY, and AbrB (Serror and Sonenshein, 1996; Hoa et al, 2002; Hamoen et al, 2003), comK transcription is activated by the transcriptional regulator DegU (Hamoen et al, 2000). When ComK levels reach a certain threshold, it binds its own promoter region to further increase its own expression, thereby creating a positive feedback loop, which leads to full activation of competence (Maamar and Dubnau, 2005; Smits et al, 2005)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
