SCAN:Control of gene expression during development in Bacillus subtilis

ITQB Scan Seminar

Title: Control of gene expression during development in Bacillus subtilis

From: Microbial Development Laboratory

Abstract:

Positive auto-regulation of a transcriptional activator during cell differentiation or development often allows the rapid and robust deployment of cell- and stage-specific genes and the routing of the differentiating cell down a specific path. Positive auto-regulation however, raises the potential for inappropriate activity of the transcription factor. We have unraveled the role of a previously characterized anti-sigma factor, CsfB, in a negative feedback loop that prevents ectopic expression of the sporulation-specific sigma factor G of Bacillus subtilis. G is activated in the forespore, one of the two chambers of the developing cell, at an intermediate stage in spore development. Once active, a positive feedback loop allows the rapid accumulation of G. Synthesis of both G and CsfB is under the control of the early forespore regulator F, and CsfB may help prevent the premature activity of G in the forespore. However, CsfB is also produced under G control in non-sporulating cells, setting a composite negative feedback loop that we show limits its ectopic activation. CsfB binds to G preventing its association with the catalytic core of RNA polymerase. However, CsfB is also able to disrupt the holoenzyme, once the transcriptionally competent complex between the sigma subunit and the core of RNA polymerase is formed.