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PROSITE documentation PDOC00814 [for PROSITE entry PS01063] |
Sigma factors [1] are bacterial transcription initiation factors that promote the attachment of the core RNA polymerase to specific initiation sites and are then released. They alter the specificity of promoter recognition. Most bacteria express a multiplicity of sigma factors. With regards to sequence similarity, sigma factors can be grouped into two classes: the sigma-54 and sigma-70 families. The sigma-70 family includes, in addition to the primary sigma factor, a wide variety of sigma factors. It also includes a divergent subfamily [2] that regulates gene encoding for proteins with extracytoplasmic function. The proteins that are currently known to belong to this sigma factor subfamily, known as ECF, are:
As a signature pattern for the ECF subfamily we chose the region that corresponds to subdomain 2.2 in classical sigma-70 factors [3]; this region seems to be involved in the binding of the sigma factor to the core RNA polymerase.
Note:See also the general entry on sigma-70 factors <PDOC00592>.
Expert(s) to contact by email: Last update:July 1998 / Pattern and text revised.
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PROSITE method (with tools and information) covered by this documentation:
1 | Authors | Helmann J.D. Chamberlin M.J. |
Title | Structure and function of bacterial sigma factors. | |
Source | Annu. Rev. Biochem. 57:839-872(1988). | |
PubMed ID | 3052291 | |
DOI | 10.1146/annurev.bi.57.070188.004203 |
2 | Authors | Lonetto M.A. Brown K.L. Rudd K.E. Buttner M.J. |
Title | Analysis of the Streptomyces coelicolor sigE gene reveals the existence of a subfamily of eubacterial RNA polymerase sigma factors involved in the regulation of extracytoplasmic functions. | |
Source | Proc. Natl. Acad. Sci. U.S.A. 91:7573-7577(1994). | |
PubMed ID | 8052622 |
3 | Authors | Lonetto M.A. Gribskov M. Gross C.A. |
Title | The sigma 70 family: sequence conservation and evolutionary relationships. | |
Source | J. Bacteriol. 174:3843-3849(1992). | |
PubMed ID | 1597408 |