DksA and ppGpp Regulate the σ Stress Response by Activating Promoters for the Small RNA DsrA and the Anti-Adapter Protein IraP.

σ is an alternative sigma factor, encoded by the gene, that redirects cellular transcription to a large family of genes in response to stressful environmental signals. This so-called σ general stress response is necessary for survival in many bacterial species and is controlled by a complex, multifactorial pathway that regulates σ levels transcriptionally, translationally, and posttranslationally in It was shown previously that the transcription factor DksA and its cofactor, ppGpp, are among the many factors governing σ synthesis, thus playing an important role in activation of the σ stress response. However, the mechanisms responsible for the effects of DksA and ppGpp have not been elucidated fully.

Stationary-Phase Mutagenesis in Stressed Bacillus subtilis Cells Operates by Mfd-Dependent Mutagenic Pathways.

In replication-limited cells of Bacillus subtilis, Mfd is mutagenic at highly transcribed regions, even in the absence of bulky DNA lesions. However, the mechanism leading to increased mutagenesis through Mfd remains currently unknown. Here, we report that Mfd may promote mutagenesis in nutritionally stressed B.

Activation of the σE-dependent stress pathway by conjugative TraR may anticipate conjugational stress.

Horizontal gene transfer by conjugation plays a major role in bacterial evolution, allowing the acquisition of new traits, such as virulence and resistance to antibacterial agents. With the increased antibiotic resistance in bacterial pathogens, a better understanding of how bacteria modulate conjugation under changing environments and the genetic factors involved is needed. Despite the evolutionary advantages conjugation may confer, the process can be quite stressful for the donor cell.