Elucidating the Function of the RpoS Regulon

Abstract

Bacterial adaptation to suboptimal nutrient environments, including host and/or extreme environments, is subject to complex, coordinated control involving many proteins and RNAs. Among the γ-proteobacteria, which includes many pathogens, the RpoS regulon has been a key focus for many years. Although the RpoS regulator was first identified as a growth phase-dependent regulator, our current understanding of RpoS is now more nuanced as this central regulator also has roles in exponential phase, biofilm development, bacterial virulence and bacterial persistence, as well as in stress adaptation. Induction of RpoS can also exert substantial metabolic effects by negatively regulating key systems including flagella biosynthesis, cryptic phage gene expression and the tricarboxylic acid cycle. Although core RpoS-controlled metabolic functions are conserved, there are substantial differences in RpoS regulation even among closely related bacteria, indicating that regulatory plasticity may be an important aspect of RpoS regulation, which is important in evolutionary adaptation to specialized environments.

The rpoS Gene Is Predominantly Inactivated during Laboratory Storage and Undergoes Source-Sink Evolution in Escherichia coli Species

“…From a practical point of view, this observation should encourage bacteriologists to make fewer subcultures and stab cultures and should instead promote the immediate freezing of isolates. This will prevent erroneous phenotyping of the strains because RpoS regulates several phenotypes, some of which are medically relevant, including biofilm development, bacterial persistence, and antibiotic resistance (62,63).…”

Protection against deleterious nitrogen compounds: role of σS-dependent small RNAs encoded adjacent tosdiA

“…The key regulator in stationary phase is σ S , encoded by the rpoS gene (10,11). This alternative sigma factor directs the expression of hundreds of genes when cells enter stationary phase or encounter other stresses, alone at some promoters and in conjunction with additional transcription factors at other promoters.…”

Genome-Wide Transcriptional Response to Varying RpoS Levels in Escherichia coli K-12

“…Transcription by RNA polymerase containing RpoS is responsible for the general stress response (4)(5)(6). Under conditions of optimal growth in the laboratory (such as exponential-phase growth in rich medium at 37°C), RpoS levels are nearly undetectable in the model strain E. coli K-12.…”

“…Under conditions of optimal growth in the laboratory (such as exponential-phase growth in rich medium at 37°C), RpoS levels are nearly undetectable in the model strain E. coli K-12. As conditions become poorer for growth, either because cells begin to starve for various nutrients or because they face physical challenges, such as low temperature or elevated osmolarity, RpoS levels rise (4)(5)(6). RpoS coordinates the transcription of genes that are critical for the response to these stresses.…”