Transcriptional Circuits and Phenotypic Variation
Ákos T. Kovács and Oscar P. Kuipers
from: Bacterial Gene Regulation and Transcriptional Networks (Edited by: M. Madan Babu). Caister Academic Press, U.K. (2013)
By developing various survival strategies simultaneously, bacterial populations are well-prepared to meet harsh conditions. The Gram-positive model organism B. subtilis presents a superb example how noise, positive- and negative feedback loops and epigenetic inheritance influence developmental pathways. Noise in combination with a fast positive autoregulatory pathway creates the possibility to initiate natural competence in a subpopulation, followed by a slow negative feedback loop to escape from the competent state when needed. In contrast, sporulation is a one-way differentiation process that is accurately timed and regulated by a gradual increase of phosphorylated Spo0A levels in conjunction with a fine-tuned autoactivation through the phosphorelay in specific activated cells. Intertwinement of regulatory pathways depending on defined levels and activities of regulators can result in genetic logic AND gates, which ensure that appropriate pathways are only activated under specific conditions in a given subpopulation of cells. Finally, communication between subpopulations of cells within an isogenic culture aids and determines the development of complex microbial communities read more ...