E.coly promoters

We will use E.coly as an example. In E.coly we can find the following consensus sequence around RNA transcription start point: nnnTTGACAnnnnnnnnnnnnnnnnnnTATAATnnnnnnNnnn. N is the transcription start point. TTGACA appears 35 bases before N, and TATAAT (also known as TATA box or Pribnow box) appear 12 bases before N. We have here 2 anchor points for the polymerase. These sequences are short but the frequency of their occurrence is high enough to stand out. There are other common features that can be used to recognize promoter regions which are beyond the scope of this lecture.