A sigma factor (σ factor) is a prokaryotic transcription initiation factor that enables specific binding of RNA polymerase to gene promoters. Different sigma factors are activated in response to different environmental conditions. Every molecule of RNA polymerase contains exactly one sigma factor subunit...
This entry initially describes the basic function of sigma factors in transcription initiation and their classification into phylogenetically and structurally distinct families. Following this, the posttranslational control of sigma factor activity, primarily by protein inhibitors called anti-sigma factors, is...
TomDefoirdt, inTrends in Microbiology, 2018 Sigma factorsare proteins that form essential subunits of prokaryotic RNA polymerase, thereby affecting gene expression[20]. They provide promoter recognition specificity to the RNA polymerase enzyme. The association of a certain sigma factor with core RNA po...
transcription regulated by both thespvRgene product, and thesigma factor RpoS, influenced in turn by such factors as the host intracellular environment, low pH, iron limitation, and nutrient limitation concurrent with reaching the stationary growth phase. The gene products ofspvABCDappear to enhance ...
It has been long a focus for scientists to answer whether the prokaryotic σ like the universal eukaryotic transcription initiation factor, the TATA box-binding protein, can be recruited to the promoter prior to association with core RNAP during transcription initiation. To answer this question, pur...
Fig. 1: Illustrative overview of the workflow to create our Promoter transcription initiation frequency (TIF) Designer tool, ProD. aMultiple promoter libraries were created, driving mKate2 expression, by engineering the promoter spacer DNA sequence to maintain the sigma factor recognition specificity. ...
Like the bacterial RNA polymerase, the PEP holoenzyme also requires a sigma factor (SIG) to specifically recognize promoter elements and initiate transcription42. There are 6 SIGs in Arabidopsis, named SIG1–6, which play unique and overlapping roles42. While the bacterial-like α, β, β’, ...
Iron-regulated transcription of ptxR from the P2 promoter, but not constitutive expression from the P1 promoter, was dependent on the Fur-regulated alternative sigma factor gene pvdS, even under aerobic conditions. Consequently, there are two levels of iron-regulated expression of ptxR. The iron-...
DNA microarray analysis of plastid gene expression in an Arabidopsis mutant deficient in a plastid transcription factor sigma, SIG2. The plastid genome of higher plants contains more than one hundred genes for photosynthesis, gene expression, and other processes. Plastid transcription is... A Nagashim...
(ECF) sigma factor family, a family that is essential for controlling transcription during stress responses and morphological changes[45]. In bothP.c.c.andP.s., another sigma factor, RpoN/sigma-54, activates the expression of HrpL (Figures 2b and 3b). In addition, specific NtrC-like ...