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J Bacteriol. Oct 1994; 176(20): 6214–6220.
PMCID: PMC196961

Functional analysis of the tdcABC promoter of Escherichia coli: roles of TdcA and TdcR.

Abstract

The efficient expression of the tdc operon of Escherichia coli requires the products of two regulatory genes, tdcR and tdcA. We have identified the transcription site of tdcR by primer extension mapping and established the translation start site of TdcR by mutational analysis of its reading frame. In a tdcR tdcABC deletion strain, tdcR+ promoted high-level LacZ expression from a lambda tdcAB-lacZ lysogen and mutations introduced in tdcR resulted in a greater than sixfold decrease in LacZ level. In-frame deletions of tdcA also reduced LacZ expression, and chromosomal and plasmid-borne tdcA+ increased the LacZ level in tdcA mutant lysogens. Interestingly, multicopy tdcA+ plasmids introduced into tdcR mutant strains completely restored tdc expression. In separate experiments we found that mutations in the tdc promoter DNA around positions -70, -140, and -175 greatly reduced tdc expression relative to that for the wild-type promoter and the tdcP mutation around -175 prevented multicopy tdcA+ from rescuing tdcR mutants. Furthermore, competition experiments revealed that a wild-type promoter fragment encompassing the -175 region cloned into a plasmid reduced tdc expression by titrating TdcA in vivo, and this effect was reversed with excess TdcA. These results suggest that in tdcR+ cells TdcR interacts with tdcP and/or TdcA to enhance tdc transcription whereas in tdcR mutant cells a new tdcP-TdcA complex around -175 in the native promoter bypasses the requirement for TdcR. On the basis of the accumulated data summarized here and elsewhere we propose that multiple transcription factors enhance tdc operon expression by bending and looping of the promoter DNA to form an active transcription complex.

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Selected References

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  • Datta P, Goss TJ, Omnaas JR, Patil RV. Covalent structure of biodegradative threonine dehydratase of Escherichia coli: homology with other dehydratases. Proc Natl Acad Sci U S A. 1987 Jan;84(2):393–397. [PMC free article] [PubMed]
  • Ganduri YL, Sadda SR, Datta MW, Jambukeswaran RK, Datta P. TdcA, a transcriptional activator of the tdcABC operon of Escherichia coli, is a member of the LysR family of proteins. Mol Gen Genet. 1993 Sep;240(3):395–402. [PubMed]
  • Goethals K, Van Montagu M, Holsters M. Conserved motifs in a divergent nod box of Azorhizobium caulinodans ORS571 reveal a common structure in promoters regulated by LysR-type proteins. Proc Natl Acad Sci U S A. 1992 Mar 1;89(5):1646–1650. [PMC free article] [PubMed]
  • Goss TJ, Datta P. Molecular cloning and expression of the biodegradative threonine dehydratase gene (tdc) of Escherichia coli K12. Mol Gen Genet. 1985;201(2):308–314. [PubMed]
  • Goss TJ, Schweizer HP, Datta P. Molecular characterization of the tdc operon of Escherichia coli K-12. J Bacteriol. 1988 Nov;170(11):5352–5359. [PMC free article] [PubMed]
  • Hobert EH, Datta P. Synthesis of biodegradative threonine dehydratase in Escherichia coli: role of amino acids, electron acceptors, and certain intermediary metabolites. J Bacteriol. 1983 Aug;155(2):586–592. [PMC free article] [PubMed]
  • Houman F, Diaz-Torres MR, Wright A. Transcriptional antitermination in the bgl operon of E. coli is modulated by a specific RNA binding protein. Cell. 1990 Sep 21;62(6):1153–1163. [PubMed]
  • Kunkel TA, Roberts JD, Zakour RA. Rapid and efficient site-specific mutagenesis without phenotypic selection. Methods Enzymol. 1987;154:367–382. [PubMed]
  • Lisser S, Margalit H. Compilation of E. coli mRNA promoter sequences. Nucleic Acids Res. 1993 Apr 11;21(7):1507–1516. [PMC free article] [PubMed]
  • Messing J. New M13 vectors for cloning. Methods Enzymol. 1983;101:20–78. [PubMed]
  • Plaskon RR, Wartell RM. Sequence distributions associated with DNA curvature are found upstream of strong E. coli promoters. Nucleic Acids Res. 1987 Jan 26;15(2):785–796. [PMC free article] [PubMed]
  • Schleif R. DNA looping. Annu Rev Biochem. 1992;61:199–223. [PubMed]
  • Schweizer HP, Datta P. Genetic analysis of the tdcABC operon of Escherichia coli K-12. J Bacteriol. 1988 Nov;170(11):5360–5363. [PMC free article] [PubMed]
  • Schweizer HP, Datta P. The complete nucleotide sequence of the tdc region of Escherichia coli. Nucleic Acids Res. 1989 May 25;17(10):3994–3994. [PMC free article] [PubMed]
  • Schweizer HP, Datta P. Identification and DNA sequence of tdcR, a positive regulatory gene of the tdc operon of Escherichia coli. Mol Gen Genet. 1989 Sep;218(3):516–522. [PubMed]
  • Schweizer HP, Datta P. Physical linkage and transcriptional orientation of the tdc operon on the Escherichia coli chromosome. Mol Gen Genet. 1991 Aug;228(1-2):125–128. [PubMed]
  • Spiro S, Guest JR. FNR and its role in oxygen-regulated gene expression in Escherichia coli. FEMS Microbiol Rev. 1990 Aug;6(4):399–428. [PubMed]
  • Sumantran VN, Schweizer HP, Datta P. A novel membrane-associated threonine permease encoded by the tdcC gene of Escherichia coli. J Bacteriol. 1990 Aug;172(8):4288–4294. [PMC free article] [PubMed]
  • Wu YF, Datta P. Integration host factor is required for positive regulation of the tdc operon of Escherichia coli. J Bacteriol. 1992 Jan;174(1):233–240. [PMC free article] [PubMed]
  • Wu Y, Patil RV, Datta P. Catabolite gene activator protein and integration host factor act in concert to regulate tdc operon expression in Escherichia coli. J Bacteriol. 1992 Nov;174(21):6918–6927. [PMC free article] [PubMed]
  • Xiong XF, de la Cruz N, Reznikoff WS. Downstream deletion analysis of the lac promoter. J Bacteriol. 1991 Aug;173(15):4570–4577. [PMC free article] [PubMed]

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