Bacterial promoters contain two consensus sequences that seem to be essential for the binding of the RNA polymerase. The first, the Pribnow box, is at - 10 b.p and has the consensus sequence 5' TATAAT 3'.

a segment upstream from the start-point of prokaryotic structural genes to which the sigma subunit of the RNA polymerase binds; the nucleotides most commonly found are TATAAT

The Pribnow box (also known as the Pribnow-Schaller box) is the sequence TATAAT of six nucleotides (thymine-adenine-thymine-etc.) that is an essential part of a promoter site on DNA for transcription to occur in prokaryotes. It is located roughly 10 base pairs upstream (that is, in the direction 5' from the first transcribed base). It is considered a consensus sequence - that is, it is the most common base sequence to appear at such points on the DNA helix; there may be variations in various organisms.