Pribnow box and other sequences common to DNA regions upstream to several operons

Content
Regulation of Gene Expression 1.  Operon Circuits in Bacteria and other Prokaryotes
Induction and repression
Inducer and co-repressor
The operon model for transcriptional regulation 
The tryptophan operon in bacteria (E. coli and Salmonella)
Tryptophan (trp) repressor controls three sets of genes
Negative and Positive Controls of Transcription
Substitution of Sigma Factor and Control of Transcription
Multiple sigma factors in E. coli 
Sporulation in bacteria
DNA sequences controlling transcription 
DNA sequences for CAP, RNA polymerase and lac-repressor
Identification of starting point
Pribnow box and other sequences common to DNA regions upstream to several operons
Regulation by DNA rearrangements
Post-transcriptional regulation
Leader sequences and attenuators
Autogenous regulation of translation
Regulation by alternative splicing
Regulation by-anti-sense RNA
Repression and activation of translation
Feedback inhibition
Signal transduction and ‘two component regulatory system’
Pribnow box and other sequences common to DNA regions upstream to several operons
Upstream to starting point of lac operon are number of sequences which are common to many E. coli and bacteriophage genes. There is a sequence at about 10 bases upstream from starting point (also called minus ten or - 10 sequence) called Pribnow box which is an important sequence and named after D. Pribnow, who first discovered it in 1975.

Pribnow box is shown in Figure 35.21 and has the following sequence in lac operon.

This sequence differs slightly from the consensus sequence for Pribnow box (TATAAT) described in the previous topic, where it was shown that among prokaryotes the range of conservation of bases varies from 45% to 96%. There are other common sequences located at -30 and -60 bases (upstream), the latter being CAP site, which is marked by an interrupted three base pair inverted repeat, flanked by non-inverted T-A base pair on either side as follows.


This CAP binding site is common to lac,gal and ara operons. It lies within -53 to -23 bp in gal operon,bctween -72 to -52bp in lac operon and between -107 to -78bp in ara operon.