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. 1992 Aug;174(16):5211–5218. doi: 10.1128/jb.174.16.5211-5218.1992

Structural analysis of the acfA and acfD genes of Vibrio cholerae: effects of DNA topology and transcriptional activators on expression.

C Parsot 1, J J Mekalanos 1
PMCID: PMC206354  PMID: 1644747

Abstract

The Vibrio cholerae acfA, B, C, and D genes are involved in the synthesis of a colonization factor; their expression is under the control of ToxR, the cholera toxin transcriptional activator. By a combination of Southern blot analysis, cloning, and nucleotide sequence analysis, we determined that the acf genes are clustered on a 5-kb region, the acfA and acfD genes are transcribed divergently, and the translation start sites of the two genes are separated by only 173 bp. Expression from the acfA and acfD promoters in V. cholerae was studied by using acfA:phoA translational and acfD-lacZ transcriptional fusions; when carried by the chromosome, the acfA-acfD intergenic region flanked by the two reporter genes was found to contain the cis-acting element(s) necessary for the environmental regulation of the two promoters. However, this regulation was almost completely abolished when the same construction was carried by a low-copy-number plasmid. These results suggested that differences in DNA topology between the plasmid versus the chromosomal constructs might influence the expression of the acfA and acfD promoters. Support for this conclusion was obtained by showing that ToxR-dependent but not basal expression of both promoters was strongly inhibited by nalidixic acid and novobiocin, two DNA gyrase inhibitors, suggesting that the activation of these promoters is affected by changes in DNA supercoiling. Expression of the acfA and acfD promoters was also investigated in the heterologous host Escherichia coli harboring plasmids expressing either ToxR or ToxT, two transcriptional activators of the V. cholerae virulence genes. ToxR activated the acfD promoter 2.5-fold but inhibited the acfA promoter 2-fold. In contrast, the expression of the acfA promoter was activated 10-fold and that of the acfD promoter was activated 3-fold by ToxT, supporting the previously proposed cascade model for organization of the ToxR regulon.

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Selected References

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  1. Casadaban M. J., Cohen S. N. Analysis of gene control signals by DNA fusion and cloning in Escherichia coli. J Mol Biol. 1980 Apr;138(2):179–207. doi: 10.1016/0022-2836(80)90283-1. [DOI] [PubMed] [Google Scholar]
  2. DiRita V. J. Co-ordinate expression of virulence genes by ToxR in Vibrio cholerae. Mol Microbiol. 1992 Feb;6(4):451–458. doi: 10.1111/j.1365-2958.1992.tb01489.x. [DOI] [PubMed] [Google Scholar]
  3. DiRita V. J. Co-ordinate expression of virulence genes by ToxR in Vibrio cholerae. Mol Microbiol. 1992 Feb;6(4):451–458. doi: 10.1111/j.1365-2958.1992.tb01489.x. [DOI] [PubMed] [Google Scholar]
  4. DiRita V. J., Parsot C., Jander G., Mekalanos J. J. Regulatory cascade controls virulence in Vibrio cholerae. Proc Natl Acad Sci U S A. 1991 Jun 15;88(12):5403–5407. doi: 10.1073/pnas.88.12.5403. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Dorman C. J., Ni Bhriain N., Higgins C. F. DNA supercoiling and environmental regulation of virulence gene expression in Shigella flexneri. Nature. 1990 Apr 19;344(6268):789–792. doi: 10.1038/344789a0. [DOI] [PubMed] [Google Scholar]
  6. Friedman A. M., Long S. R., Brown S. E., Buikema W. J., Ausubel F. M. Construction of a broad host range cosmid cloning vector and its use in the genetic analysis of Rhizobium mutants. Gene. 1982 Jun;18(3):289–296. doi: 10.1016/0378-1119(82)90167-6. [DOI] [PubMed] [Google Scholar]
  7. Galán J. E., Curtiss R., 3rd Expression of Salmonella typhimurium genes required for invasion is regulated by changes in DNA supercoiling. Infect Immun. 1990 Jun;58(6):1879–1885. doi: 10.1128/iai.58.6.1879-1885.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Göransson M., Sondén B., Nilsson P., Dagberg B., Forsman K., Emanuelsson K., Uhlin B. E. Transcriptional silencing and thermoregulation of gene expression in Escherichia coli. Nature. 1990 Apr 12;344(6267):682–685. doi: 10.1038/344682a0. [DOI] [PubMed] [Google Scholar]
  9. Herrington D. A., Hall R. H., Losonsky G., Mekalanos J. J., Taylor R. K., Levine M. M. Toxin, toxin-coregulated pili, and the toxR regulon are essential for Vibrio cholerae pathogenesis in humans. J Exp Med. 1988 Oct 1;168(4):1487–1492. doi: 10.1084/jem.168.4.1487. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Hulton C. S., Seirafi A., Hinton J. C., Sidebotham J. M., Waddell L., Pavitt G. D., Owen-Hughes T., Spassky A., Buc H., Higgins C. F. Histone-like protein H1 (H-NS), DNA supercoiling, and gene expression in bacteria. Cell. 1990 Nov 2;63(3):631–642. doi: 10.1016/0092-8674(90)90458-q. [DOI] [PubMed] [Google Scholar]
  11. Lipman D. J., Pearson W. R. Rapid and sensitive protein similarity searches. Science. 1985 Mar 22;227(4693):1435–1441. doi: 10.1126/science.2983426. [DOI] [PubMed] [Google Scholar]
  12. Manoil C., Beckwith J. TnphoA: a transposon probe for protein export signals. Proc Natl Acad Sci U S A. 1985 Dec;82(23):8129–8133. doi: 10.1073/pnas.82.23.8129. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Mekalanos J. J. Environmental signals controlling expression of virulence determinants in bacteria. J Bacteriol. 1992 Jan;174(1):1–7. doi: 10.1128/jb.174.1.1-7.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Miller V. L., DiRita V. J., Mekalanos J. J. Identification of toxS, a regulatory gene whose product enhances toxR-mediated activation of the cholera toxin promoter. J Bacteriol. 1989 Mar;171(3):1288–1293. doi: 10.1128/jb.171.3.1288-1293.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Miller V. L., Mekalanos J. J. A novel suicide vector and its use in construction of insertion mutations: osmoregulation of outer membrane proteins and virulence determinants in Vibrio cholerae requires toxR. J Bacteriol. 1988 Jun;170(6):2575–2583. doi: 10.1128/jb.170.6.2575-2583.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Miller V. L., Mekalanos J. J. Synthesis of cholera toxin is positively regulated at the transcriptional level by toxR. Proc Natl Acad Sci U S A. 1984 Jun;81(11):3471–3475. doi: 10.1073/pnas.81.11.3471. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Miller V. L., Taylor R. K., Mekalanos J. J. Cholera toxin transcriptional activator toxR is a transmembrane DNA binding protein. Cell. 1987 Jan 30;48(2):271–279. doi: 10.1016/0092-8674(87)90430-2. [DOI] [PubMed] [Google Scholar]
  18. Parsot C. Evolution of biosynthetic pathways: a common ancestor for threonine synthase, threonine dehydratase and D-serine dehydratase. EMBO J. 1986 Nov;5(11):3013–3019. doi: 10.1002/j.1460-2075.1986.tb04600.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Parsot C., Mekalanos J. J. Expression of the Vibrio cholerae gene encoding aldehyde dehydrogenase is under control of ToxR, the cholera toxin transcriptional activator. J Bacteriol. 1991 May;173(9):2842–2851. doi: 10.1128/jb.173.9.2842-2851.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Parsot C., Taxman E., Mekalanos J. J. ToxR regulates the production of lipoproteins and the expression of serum resistance in Vibrio cholerae. Proc Natl Acad Sci U S A. 1991 Mar 1;88(5):1641–1645. doi: 10.1073/pnas.88.5.1641. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Peterson K. M., Mekalanos J. J. Characterization of the Vibrio cholerae ToxR regulon: identification of novel genes involved in intestinal colonization. Infect Immun. 1988 Nov;56(11):2822–2829. doi: 10.1128/iai.56.11.2822-2829.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Sanger F., Nicklen S., Coulson A. R. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. doi: 10.1073/pnas.74.12.5463. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Strauch K. L., Beckwith J. An Escherichia coli mutation preventing degradation of abnormal periplasmic proteins. Proc Natl Acad Sci U S A. 1988 Mar;85(5):1576–1580. doi: 10.1073/pnas.85.5.1576. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Taylor R. K., Miller V. L., Furlong D. B., Mekalanos J. J. Use of phoA gene fusions to identify a pilus colonization factor coordinately regulated with cholera toxin. Proc Natl Acad Sci U S A. 1987 May;84(9):2833–2837. doi: 10.1073/pnas.84.9.2833. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Wu H. C., Tokunaga M. Biogenesis of lipoproteins in bacteria. Curr Top Microbiol Immunol. 1986;125:127–157. doi: 10.1007/978-3-642-71251-7_9. [DOI] [PubMed] [Google Scholar]
  26. Yanisch-Perron C., Vieira J., Messing J. Improved M13 phage cloning vectors and host strains: nucleotide sequences of the M13mp18 and pUC19 vectors. Gene. 1985;33(1):103–119. doi: 10.1016/0378-1119(85)90120-9. [DOI] [PubMed] [Google Scholar]

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