Structure and Function of Bacterial Sigma Factors

Two types of localization of the DNA‐binding proteins within the Escherichia coli nucleoid

“…The RNA polymerase core enzyme with subunit composition of a 2 bb H is associated with template DNA during one cycle of transcription from promoters to terminators, while the s subunits are dissociated after initiation for cyclic re-use in another initiation (Helmann & Chamberlin 1988;Gross et al 1992). Here we have analysed the distribution of the a subunit to demonstrate the location of core enzyme, and of the subunit s 70 which recognizes the promoters for growth-related genes.…”

Modulation of the nucleoid, the transcription apparatus, and the translation machinery in bacteria for stationary phase survival

“…3), each participates in the transcription of a specific set of genes (Helmann & Chamberlin 1988;Ishihama 1988;Gross et al 1992Gross et al , 1997a Figure 3 Seven species of sigma factors for the specificity control of E. coli RNA polymerase. The RNA polymerase holoenzyme of E. coli is composed of the core enzyme with the subunit composition ␣ 2 ␤␤ 0 and one of seven different molecular species of subunit, which confer the promoter recognition activity.…”

DNA Binding Specificity of Mu Transcription Factor C and Crystallization of C : DNA Complex

“…There are seven different species of the σ subunit identified in Escherichia coli (E.coli) (Gross et al, 1998;Helmann and Figure 1-1. Domain organization of σ 70 into various conserved regions with their identified functions.…”

“…This sigma is present at all times in the bacterial cell and is important for turning on genes involved in nitrogen regulation. There are four flexible domains in σ 70 referred to as σ 1.1 , σ 2 , σ 3 and σ 4 (Helmann and Chamberlin, 1988) ( Figure 1-1). Each domain contains one or more highly conserved regions; 1.1 and 1.2, 2.1-2.4, 3.1-3.2 and 4.1-4.2 (Malhotra et al, 1996;Gross, 1998;Borukhov and Severinov, 2002;Campbell et al, 2002;Murakami et al, 2002;Vassylyev et al, 2002;Murakami and Darst, 2003).…”

“…The σ 70 cannot bind the promoter on its own since region 1.1 masks region 2.4 and region 4.2; and binding inhibition is only released after sigma binds the core RNAP. The σ 70 can also direct transcription from extended -10 promoters that do not have a good -35 hexamer (Helmann and Chamberlin, 1988). Region 2.5 (not shown) makes supplementary contact with the extended -10 motif (Barne et al, 1997).…”