title: Anti-Sigma Factors in E. coli: Common Regulatory Mechanisms Controlling Sigma Factors Availability.
abstract: In bacteria, transcriptional regulation is a key step in cellular gene expression. All bacteria contain a core RNA polymerase that is catalytically competent but requires an additional σ factor for specific promoter recognition and correct transcriptional initiation. The RNAP core is not able to selectively bind to a given σ factor. In contrast, different σ factors have different affinities for the RNAP core. As a consequence, the concentration of alternate σ factors requires strict regulation in order to properly control the delicate interplay among them, which favors the competence for the RNAP core. This control is archived by different σ/anti-σ controlling mechanisms that shape complex regulatory networks and cascades, and enable the response to sudden environmental cues, whose global understanding is a current challenge for systems biology. Although there have been a number of excellent studies on each of these σ/anti-σ post-transcriptional regulatory systems, no comprehensive comparison of these mechanisms in a single model organism has been conducted. Here, we survey all these systems in E. coli dissecting and analyzing their inner workings and highlightin their differences. Then, following an integral approach, we identify their commonalities and outline some of the principles exploited by the cell to effectively and globally reprogram the transcriptional machinery. These principles provide guidelines for developing biological synthetic circuits enabling an efficient and robust response to sudden stimuli.
authors.affiliation: Departamento de Tecnología Ambiental, Universidad Politécnica del Estado de Morelos. Blvd. Cuauhnáhuac 566, Col. Lomas del Texcal, 62550. Jiutepec, Morelos, México;
authors.forename: Luis Gerardo
authors.initials: LG
authors.lastname: Treviño-Quintanilla
authors.affiliation: Programa de Genómica Evolutiva, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México. Av. Universidad s/n, Col. Chamilpa, 62210. Cuernavaca, Morelos, México;
authors.forename: Julio Augusto
authors.initials: JA
authors.lastname: Freyre-González
authors.affiliation: Departamento de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México. Apdo. Postal 510-3, 62250. Cuernavaca, Morelos, México.
authors.forename: Irma
authors.initials: I
authors.lastname: Martínez-Flores
keywords: Anti-sigma factors; Escherichia coli; Homeostasis; Negative feedback; Sigma factors; Transcriptional regulation.