Editing Promoter (genetics) (section)

==Overview==
For transcription to take place, the enzyme that synthesizes RNA, known as [[RNA polymerase]], must attach to the DNA near a gene. Promoters contain specific DNA sequences such as [[response elements]] that provide a secure initial binding site for RNA polymerase and for proteins called [[transcription factors]] that recruit RNA polymerase. These transcription factors have specific [[Activator (genetics)|activator]] or [[repressor]] sequences of corresponding nucleotides that attach to specific promoters and regulate gene expression.{{cn|date=June 2024}}

;In [[bacteria]]: The promoter is recognized by RNA polymerase and an associated [[sigma factor]], which in turn are often brought to the promoter DNA by an activator protein's binding to its own [[DNA binding site]] nearby.
;In [[eukaryotes]]: The process is more complicated, and at least seven different factors are necessary for the binding of an [[RNA polymerase II]] to the promoter.
;In [[archaea]]: The promoter resembles a eukaryotic one, though much simplified. It contains BRE and TATA elements and are recognized by TFB and TBP.<ref name="pmid33112729">{{cite journal |last1=Wenck |first1=BR |last2=Santangelo |first2=TJ |title=Archaeal transcription. |journal=Transcription |date=October 2020 |volume=11 |issue=5 |pages=199–210 |doi=10.1080/21541264.2020.1838865 |pmid=33112729 |pmc=7714419}}</ref>

Promoters represent critical elements that can work in concert with other regulatory regions ([[Enhancer (genetics)|enhancer]]s, [[silencer (DNA)|silencers]], boundary elements/[[Insulator (genetics)|insulators]]) to direct the level of transcription of a given gene.
A promoter is induced in response to changes in abundance or conformation of regulatory proteins in a cell, which enable activating transcription factors to recruit RNA polymerase.<ref name="pmid24825771">{{cite journal | vauthors = Yaniv M | title = Chromatin remodeling: from transcription to cancer | journal = Cancer Genetics | volume = 207 | issue = 9 | pages = 352–7 | date = September 2014 | pmid = 24825771 | doi = 10.1016/j.cancergen.2014.03.006 }}</ref><ref name="pmid16380379">{{cite journal | vauthors = Civas A, Génin P, Morin P, Lin R, Hiscott J | title = Promoter organization of the interferon-A genes differentially affects virus-induced expression and responsiveness to TBK1 and IKKepsilon | journal = The Journal of Biological Chemistry | volume = 281 | issue = 8 | pages = 4856–66 | date = February 2006 | pmid = 16380379 | doi = 10.1074/jbc.M506812200 | doi-access = free }}</ref>

Given the short sequences of most promoter elements, promoters can rapidly evolve from random sequences. For instance, in [[Escherichia coli|''E. coli'']], ~60% of random sequences can evolve expression levels comparable to the wild-type [[Lac operon|lac promoter]] with only one mutation, and that ~10% of random sequences can serve as active promoters even without evolution.<ref>{{cite journal |vauthors=Yona AH, Alm EJ, Gore J |date=April 2018 |title=Random sequences rapidly evolve into de novo promoters |journal=Nature Communications |language=En |volume=9 |issue=1 |pages=1530 |bibcode=2018NatCo...9.1530Y |doi=10.1038/s41467-018-04026-w |pmc=5906472 |pmid=29670097}}</ref>