Promoters

Promoter + Regulatory Elements

Definition
A DNA sequence located upstream to a coding region which binds the transcription complex thus allowing transcription initiation.

Background
The promotor is positioned 10-100 nucleotides upstream of the ribosome binding site. The ideal promoter exhibits the following features:

It is strong enough to allow product accumulation up to 50% of the total cellular protein.
It exhibits a minimal level of basal transcription (a highly repressible promoter is especially important, when the protein of interest is toxic or detrimental to the growth of the host cell).
It is easy to induce.

Frequently Used Promoters

Further Reading

Related Database & Software

Search Commercially Available Vectors

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Related Database & Software

PromEC - a database of E. coli mRNA promoters with experimentally identified transcriptional start sites
EPD - Eukaryotic Promoter Database.
Promoter Scan - Predicts Promoter regions based on scoring homologies with putative eukaryotic Pol II promoter sequences.
Promoter 2.0 Prediction Server predicts transcription start sites of vertebrate PolII promoters in DNA sequences.
SCPD - The Promoter Database of Saccharomyces cerevisiae

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**Frequently Used** **Promoters**
For bacterial cells For insect cells For mammalian cells
Promoter	Suitable for	Source	Regulation	Induction	Level of Expression	Additional Information	Further Documentation
lac	Bacterial cells	E. coli	lacI, lacI^{q *}	IPTG	low		lac operon - animation lac & trp operons
lacUV5	Bacterial cells	E. coli	lacI, lacI^{q *}	IPTG	low	Theoretically not subject to cAMP dependent regulation
tac (hybrid)	Bacterial cells	E. coli	lacI, lacI^{q *}	IPTG	Allows accumulation of protein to about 15-30% of total cell protein	Consists of the -35 region of the trp promoter and the -10 region of the lac promoter (differs from the trc promoter by 1 bp)
trc (hybrid)	Bacterial cells	E. coli	lacI, lacI^{q *}	IPTG	Allows accumulation of protein to about 15-30% of total cell protein	Consists of the -35 region of the trp promoter and the -10 region of the lac promoter (differs from the tac promoter by 1 bp)
trp	Bacterial cells	E. coli	Addition of fructose to the growth medium increases down regulation under non- induced conditions.	Tryptophan starvation or addition of B-indoleacrylic acid			lac & trp operons
araBAD	Bacterial cells	E. coli	araC	l-arabinose	Somewhat weaker than the tac promoter	There is extensive heterogeneity in cell populations treated with subsaturating concentrations of l-arabinose (some bacteria are fully induced and others not at all).
phoA	Bacterial cells	E. coli	phoB (positive) phoR (negative)	phosphate starvation		Tightly controlled. Induction requires phosphate starvation, and so can limit the duration of protein synthesis.
recA	Bacterial cells	E. coli	lexA	nalidixic acid
proU	Bacterial cells	E. coli		osmolarity
cst-1	Bacterial cells	E. coli		glucose starvation
tetA	Bacterial cells	E. coli		tetracyclin
cadA	Bacterial cells	E. coli	cadR	pH
nar	Bacterial cells	E. coli	fnr	anearobic conditions
p_L	Bacterial cells	l	l cIts857	thermal (shift to 42°C)	moderately high	A phage-encoded cL repressor encodes a repressor, typically expressed from an integrated copy of a phage in the host genome. the repressor is temperature-sensitive and is functional at lower temperatures but denatures at temperatures higher then 37.5?C. Therefor the induction of expression is by a simple temp. shift.
cspA	Bacterial cells	E. coli		Thermal cold shock (shift to below 20°C)		The cspA core promoter is only weakly induced by temp. downshift. A 159 nucleotide long untranslated region at the 5' end of cspA driven transcripts makes them highly unstable at 37^oc and significantly increases their stability at low temps. This region also favors their engagement by a cold modified translational machinery. The cspA system becomes repressed 1-2 hours after temp. downshift.	Scale-up and optimization of the low-temperature inducible cspA promoter system. Cold-inducible promoters for heterologous protein expression.
SP6	Bacterial cells	Salmonella phage
T7	Bacterial cells	T7 phage	l cIts857	thermal
T7-lac operator	Bacterial cells	T7 phage	lacI^{q *}	IPTG	Allows accumulation of protein to about 40-50% of total cell protein
T3-lac operator	Bacterial cells	T3 phage	lacI^{q *}	IPTG
T5-lac operator	Bacterial cells	T5 phage	lacI, lacI^{q *}	IPTG		This promoter is recognized by the E. coli RNA polymerase
T4 gene 32	Bacterial cells	T4 phage		T4 infection
nprM-lac operator	Bacterial cells	Bacillus	lacI^{q *}	IPTG
VHb	Bacterial cells	Vitreoscilla		oxygen
Protein A	Bacterial cells	S. aureus
Promoter	Suitable for	Source	Regulation	Induction	Level of Expression	Additional Information	Further Documentation
polyhedrin	Insect cells	Baculovirus			High	A late promoter. Activated in the last stage of infection (36-72 hrs post infection) . The most active promoter in the baculovirus genome. Useful for expression of toxic proteins.
p10	Insect cells	Baculovirus			High (slightly less than polyhedrin)	A late promoter (slightly earlier than polyhedrin).
IE-0	Insect cells	Baculovirus				An early promoter (6-8 hrs post infection). Proteins are translated with more efficient post -translational modifications (due to better state of cellular functions).
PCNA	Insect cells	Baculovirus				An early promoter (6-8 hrs post infection). Proteins are translated with more efficient post -translational modifications (due to better state of cellular functions).
OplE2	Insect cells	Baculovirus		Constitutive transcription	High - (About 5-10 times stronger than OplE1 promoter)	An immediate early promoter.
OplE1	Insect cells	Baculovirus		Constitutive transcription	About 5-10 times weaker than OplE2 promoter.	An immediate early promoter.
Metallothionein	Insect cells	Drosophila		Copper Sulfate or Cadmium Chloride
Actin 5c	Insect cells	Drosophila		Constitutive transcription	High

* The lacI^qallele contains a single nucleotide mutation in the -35 hexamer of the chromosomal lacI promoter, which leads to an increase in the number of lacI repressor molecules from 10-20 to over 100 per cell.

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