Protein Family Models

Region 4 of sigma-70 like sigma-factors are involved in binding to the -35 promoter element via a helix-turn-helix motif [1]. Due to the way Pfam works, the threshold has been set artificially high to prevent overlaps with other helix-turn-helix families. Therefore there are many false negatives. [1]. 11931761. Structure of the bacterial RNA polymerase promoter specificity. sigma subunit.. Campbell EA, Muzzin O, Chlenov M, Sun JL, Olson CA, Weinman O,. Trester-Zedlitz ML, Darst SA;. Mol Cell 2002;9:527-539. (from Pfam)

Date:

2024-08-14

This HMM hits a core region shared by multiple sigma factors, interchangeable subunits that complete the RNA polymerase holoenzyme and allow transcription to start. In E. coli K-12 alone, this HMM hits RpoD (sigma-70), RpoH (sigma-32), FliA (sigma-28), FecI (sigma-19), RpoS, and RpoE.

Date:

2024-08-14

Date:

2024-08-14

This model encompasses all varieties of the sigma-70 type sigma factors including the ECF subfamily. A number of sigma factors have names with a different number than 70 (i.e. sigma-38), but in fact, all except for the Sigma-54 family (TIGR02395) are included within this family. Several PFAM models hit segments of these sequences including Sigma-70 region 2 (PF04542) and Sigma-70, region 4 (PF04545), but not always above their respective trusted cutoffs.

Date:

2024-06-27

A sigma factor is a DNA-binding protein protein that binds to the DNA-directed RNA polymerase core to produce the holoenzyme capable of initiating transcription at specific sites. Different sigma factors act in vegetative growth, heat shock, extracytoplasmic functions (ECF), etc. This model represents the clade of sigma factors called RpoH and further restricted to the Proteobacteria. This protein may be called sigma-32, sigma factor H, heat shock sigma factor, and alternative sigma factor RpoH. Note that in some species the single locus rpoH may be replaced by two or more differentially regulated stress response sigma factors.

Gene:

rpoH

Date:

2024-05-30

Binds with the catalytic core of RNA polymerase to produce the holoenzyme; this sigma factor is responsible for the expression of heat shock promoters

Date:

2021-03-12