| Description | 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 sigma-54, or RpoN (unrelated to sigma 70-type factors such as RpoD/SigA). RpoN is responsible for enhancer-dependent transcription, and its presence characteristically is associated with varied panels of activators, most of which are enhancer-binding proteins (but see Brahmachary, et al., PMID:15231786). RpoN may be responsible for transcription of nitrogen fixation genes, flagellins, pilins, etc., and synonyms for the gene symbol rpoN, such as ntrA, reflect these observations |
| Literature References | [ 1 ]Merrick MJ In a class of its own--the RNA polymerase sigma factor sigma 54 (sigma N). Mol Microbiol. 1993 Dec;10(5):903-9. PMID 7934866
[ 2 ]Buck M, Gallegos MT, Studholme DJ, Guo Y, Gralla JD The bacterial enhancer-dependent sigma(54) (sigma(N)) transcription factor. J Bacteriol. 2000 Aug;182(15):4129-36. PMID 10894718
[ 3 ]Reitzer L, Schneider BL Metabolic context and possible physiological themes of sigma(54)-dependent genes in Escherichia coli. Microbiol Mol Biol Rev. 2001 Sep;65(3):422-44, table of contents. PMID 11528004
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