LacUV5

The lacUV5 promoter is a variant of the wild type Escherichia coli lac core promoter. It contains a 2 base pair mutation in the -10 hexamer region, compared to the lac promoter.[1] By conforming closer to the sigma 70 consensus sequence, RNA Polymerase(RNAP) is recruited to the promoter more effectively, even in the absence of additional RNAP interactions via the C-terminal domain (CTD) of the alpha subunit of RNAP. Thus, transcription from lacUV5 will occur at higher rates than seen with Plac. Additionally, unlike Plac, PlacUV5 works independently of activator proteins or other cis regulatory elements (apart from the -10 and -35 promoter regions ).[2] The lacUV5 promoter is commonly found on expression plasmids and is used when controllable but high levels of a product are desired.

The lacUV5 promoter expression is regulated by the LacI repressor and can be induced with isopropyl thiogalactoside (IPTG). IPTG is an effective inducer of protein expression when used in the concentration range of 100μM to 1.5mM.

The lacUV5 promoter is often found on plasmids used to express protein fusions for further study.

References

  1. ↑ Pribnow, D. (1975) Bacteriophage T7 Early Promoters: Nucleotide Sequences of Two RNA Polymerase Binding Sites. Retrieved from http://www.sciencedirect.com/science/article/pii/S0022283675801367
  2. ↑ Noel, R.J., Reznikoff, W.S., ‘Structural Studies of lacUV5-RNA Polymerase Interactions in Vitro’, The Journal of Biological Chemistry, Vol. 275, No. 11, pp. 7708-7712, 2000. Print.