Role of Autoregulation and Relative Synthesis of Operon Partners in Alternative Sigma Factor Networks

• Published in: PLoS computational biology 2016-12, Vol.12 (12), p.e1005267-e1005267
• Main Authors: Narula, Jatin, Tiwari, Abhinav, Igoshin, Oleg A
• Format: Article
• Language: English
• Subjects: Antibiotics; Bacillus subtilis; Bacillus subtilis - genetics; Bacillus subtilis - metabolism; Bacillus subtilis - physiology; Bacteria; Bioengineering; Biology and Life Sciences; Competition; Computer and Information Sciences; Engineering and Technology; Funding; Gene expression; Gene Expression Regulation, Bacterial - physiology; Kinases; Models, Biological; Neural circuitry; Operon - physiology; Operons; Phosphatase; Physiological aspects; Proteins; RNA polymerase; Sigma Factor - metabolism; Simulation; Stress response; Stress, Physiological - physiology
• ISSN: 1553-7358; 1553-734X; 1553-7358
• DOI: 10.1371/journal.pcbi.1005267

Despite the central role of alternative sigma factors in bacterial stress response and virulence their regulation remains incompletely understood. Here we investigate one of the best-studied examples of alternative sigma factors: the σB network that controls the general stress response of Bacillus subtilis to uncover widely relevant general design principles that describe the structure-function relationship of alternative sigma factor regulatory networks. We show that the relative stoichiometry of the synthesis rates of σB, its anti-sigma factor RsbW and the anti-anti-sigma factor RsbV plays a critical role in shaping the network behavior by forcing the σB network to function as an ultrasensitive negative feedback loop. We further demonstrate how this negative feedback regulation insulates alternative sigma factor activity from competition with the housekeeping sigma factor for RNA polymerase and allows multiple stress sigma factors to function simultaneously with little competitive interference.