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:

2024-10-16

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:

2024-10-16

Region 3 forms a discrete compact three helical domain within the sigma-factor. Region is not normally involved in the recognition of promoter DNA, but as some specific bacterial promoters containing an extended -10 promoter element, residues within region 3 play an important role. Region 3 primarily is involved in binding the core RNA polymerase in the holoenzyme [1]. [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:

2024-10-16

Date:

2024-08-14

RNA polymerase sigma factor similar to Streptomyces coelicolor RNA polymerase principal sigma factor HrdA and HrdB/SigA; sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released

Date:

2023-06-02

Date:

2021-10-18

Date:

2021-08-30

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

This model represents the well-conserved C-terminal region of the major, essential sigma factor of most bacteria. Members of this clade show considerable variability in domain architecture and molecular weight, as well as in nomenclature: RpoD in E. coli and other Proteobacteria, SigA in Bacillus subtilis and many other Gram-positive bacteria, HrdB in Streptomyces, MysA in Mycobacterium smegmatis, etc.

Gene:

rpoD

Date:

2024-05-30

Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released; sigma factors in this cluster are active during stationary phase

Gene:

sigB

Date:

2020-10-26