Jun 9, 2019

ECF σ factors with regulatory extensions: the one-component systems of the σ universe

Molecular Microbiology
Daniela PintoThorsten Mascher

Abstract

The σ subunit of the bacterial RNA polymerase determines promoter specificity. The extracytoplasmic function σ factors (ECFs) represent the most abundant and diverse group of alternative σ factors and are present in the vast majority of bacterial genomes. Typically, ECFs are regulated by anti-σ factors that sequester their cognate ECFs, thereby preventing their interaction with the RNA polymerase. Beyond these ECF paradigms, a number of distinct modes of regulation have been proposed and experimentally investigated. Regulatory extensions represent one such alternative mechanism of ECF regulation that can be found in 18 phylogenetically distinct ECF groups. Here, the σ factors contain additional domains that are fused to the ECF core domains and are involved in stimulus perception and modulation of σ factor activity. We will summarize the current state of knowledge on regulating ECF activity by C-terminal extensions. We will also discuss newly identified ECF groups containing either N- or C-terminal extensions and propose possible mechanisms by which these extensions have been generated and affect ECF σ factor activity. Based on their modular architecture and the resulting physical connection between stimulus perception and tran...Continue Reading

Mentioned in this Paper

Genome
Regulation of Biological Process
DNA-Directed RNA Polymerase
Transcription, Genetic
Promoter
Nitrogen
Stimulus Sensing
Terminal (End Postition)
Composite Architecture
Gene Regulatory Networks

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