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Proc Natl Acad Sci U S A. Jan 1983; 80(1): 21–25.
PMCID: PMC393301

The tac promoter: a functional hybrid derived from the trp and lac promoters.


Two hybrid promoters that are functional in Escherichia coli have been constructed. These hybrid promoters, tacI and tacII, were derived from sequences of the trp and the lac UV5 promoters. In the first hybrid promoter (tacI), the DNA upstream of position -20 with respect to the transcriptional start site was derived from the trp promoter. The DNA downstream of position -20 was derived from the lac UV5 promoter. In the second hybrid promoter (tacII), the DNA upstream of position -11 at the Hpa I site within the Pribnow box was derived from the trp promoter. The DNA downstream of position -11 is a 46-base-pair synthetic DNA fragment that specifies part of the hybrid Pribnow box and the entire lac operator. It also specifies a Shine-Dalgarno sequence flanked by two unique restriction sites (portable Shine-Dalgarno sequence). The tacI and the tacII promoters respectively direct transcription approximately 11 and 7 times more efficiently than the derepressed parental lac UV5 promoter and approximately 3 and 2 times more efficiently than the trp promoter in the absence of the trp repressor. Both hybrid promoters can be repressed by the lac repressor and both can be derepressed with isopropyl beta-D-thiogalactoside. Consequently, these hybrid promoters are useful for the controlled expression of foreign genes at high levels in E. coli. In contrast to the trp and the lac UV5 promoters, the tacI promoter has not only a consensus -35 sequence but also a consensus Pribnow box sequence. This may explain the higher efficiency of this hybrid promoter with respect to either one of the parental promoters.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Rosenberg M, Court D. Regulatory sequences involved in the promotion and termination of RNA transcription. Annu Rev Genet. 1979;13:319–353. [PubMed]
  • Siebenlist U, Simpson RB, Gilbert W. E. coli RNA polymerase interacts homologously with two different promoters. Cell. 1980 Jun;20(2):269–281. [PubMed]
  • Pribnow D. Bacteriophage T7 early promoters: nucleotide sequences of two RNA polymerase binding sites. J Mol Biol. 1975 Dec 15;99(3):419–443. [PubMed]
  • Schaller H, Gray C, Herrmann K. Nucleotide sequence of an RNA polymerase binding site from the DNA of bacteriophage fd. Proc Natl Acad Sci U S A. 1975 Feb;72(2):737–741. [PMC free article] [PubMed]
  • Johnsrud L. Contacts between Escherichia coli RNA polymerase and a lac operon promoter. Proc Natl Acad Sci U S A. 1978 Nov;75(11):5314–5318. [PMC free article] [PubMed]
  • Goeddel DV, Heyneker HL, Hozumi T, Arentzen R, Itakura K, Yansura DG, Ross MJ, Miozzari G, Crea R, Seeburg PH. Direct expression in Escherichia coli of a DNA sequence coding for human growth hormone. Nature. 1979 Oct 18;281(5732):544–548. [PubMed]
  • Sadler JR, Tecklenburg M, Betz JL. Plasmids containing many tandem copies of a synthetic lactose operator. Gene. 1980 Feb;8(3):279–300. [PubMed]
  • Yanofsky C. Attenuation in the control of expression of bacterial operons. Nature. 1981 Feb 26;289(5800):751–758. [PubMed]
  • Heyneker HL, Shine J, Goodman HM, Boyer HW, Rosenberg J, Dickerson RE, Narang SA, Itakura K, Lin S, Riggs AD. Synthetic lac operator DNA is functional in vivo. Nature. 1976 Oct 28;263(5580):748–752. [PubMed]
  • Carpousis AJ, Stefano JE, Gralla JD. 5' nucleotide heterogeneity and altered initiation of transcription at mutant lac promoters. J Mol Biol. 1982 Jun 5;157(4):619–633. [PubMed]
  • Stefano JE, Gralla JD. Spacer mutations in the lac ps promoter. Proc Natl Acad Sci U S A. 1982 Feb;79(4):1069–1072. [PMC free article] [PubMed]

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