Skip to main content
PMC home page
Journal of Bacteriology logoLink to Journal of Bacteriology
. 1995 Oct;177(19):5401–5410. doi: 10.1128/jb.177.19.5401-5410.1995

Five promoters integrate control of the cob/pdu regulon in Salmonella typhimurium.

P Chen 1, M Ailion 1, T Bobik 1, G Stormo 1, J Roth 1
PMCID: PMC177344  PMID: 7559322

Abstract

Propanediol is degraded by a B12-dependent pathway in Salmonella typhimurium. The enzymes for this pathway are encoded in a small region (minute 41) that includes the pdu operon (controlling B12-dependent degradation of propanediol) and the divergent cob operon (controlling synthesis of cobalamin, B12). Expression of both operons is induced by propanediol and globally controlled by the ArcA and Crp systems. The region between the two operons encodes two proteins, PduF, a transporter of propanediol, and PocR, which mediates the induction of the regulon by propanediol. Insertion mutations between the pdu and cob operons have been characterized, and their exact positions have been correlated with mutant phenotypes. The region includes five promoters, four of which are controlled by the PocR protein and induced by propanediol. The cob and pdu operons each have one regulated promoter; the pduF gene is expressed from two regulated promoters (P1 and P2). The P1 and P2 transcripts extend beyond pduF to include the pocR gene; thus the PocR protein autoregulates its expression from these promoters. The fifth promoter, PPoc, is adjacent to the pocR gene and associated with a Crp binding site. We suggest that all global control of the regulon is exerted by regulating the level of PocR protein at the P1, P2, and PPoc promoters. A putative binding site for the PocR protein has been identified by computer analysis. Eight close matches to this proposed site were found in regions near the four promoters known to be regulated by PocR protein: PPdu, P1, P2, and PCob. A three-state model is proposed in which the regulon uses all five of its promoters to control expression.

Full Text

The Full Text of this article is available as a PDF (400.4 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Aiba H., Adhya S., de Crombrugghe B. Evidence for two functional gal promoters in intact Escherichia coli cells. J Biol Chem. 1981 Nov 25;256(22):11905–11910. [PubMed] [Google Scholar]
  2. Ailion M., Bobik T. A., Roth J. R. Two global regulatory systems (Crp and Arc) control the cobalamin/propanediol regulon of Salmonella typhimurium. J Bacteriol. 1993 Nov;175(22):7200–7208. doi: 10.1128/jb.175.22.7200-7208.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Andersson D. I. Involvement of the Arc system in redox regulation of the Cob operon in Salmonella typhimurium. Mol Microbiol. 1992 Jun;6(11):1491–1494. doi: 10.1111/j.1365-2958.1992.tb00869.x. [DOI] [PubMed] [Google Scholar]
  4. Berkowitz D., Hushon J. M., Whitfield H. J., Jr, Roth J., Ames B. N. Procedure for identifying nonsense mutations. J Bacteriol. 1968 Jul;96(1):215–220. doi: 10.1128/jb.96.1.215-220.1968. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Bobik T. A., Ailion M., Roth J. R. A single regulatory gene integrates control of vitamin B12 synthesis and propanediol degradation. J Bacteriol. 1992 Apr;174(7):2253–2266. doi: 10.1128/jb.174.7.2253-2266.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Carra J. H., Schleif R. F. Variation of half-site organization and DNA looping by AraC protein. EMBO J. 1993 Jan;12(1):35–44. doi: 10.1002/j.1460-2075.1993.tb05629.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Castilho B. A., Olfson P., Casadaban M. J. Plasmid insertion mutagenesis and lac gene fusion with mini-mu bacteriophage transposons. J Bacteriol. 1984 May;158(2):488–495. doi: 10.1128/jb.158.2.488-495.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Chan R. K., Botstein D., Watanabe T., Ogata Y. Specialized transduction of tetracycline resistance by phage P22 in Salmonella typhimurium. II. Properties of a high-frequency-transducing lysate. Virology. 1972 Dec;50(3):883–898. doi: 10.1016/0042-6822(72)90442-4. [DOI] [PubMed] [Google Scholar]
  9. Chen P., Ailion M., Weyand N., Roth J. The end of the cob operon: evidence that the last gene (cobT) catalyzes synthesis of the lower ligand of vitamin B12, dimethylbenzimidazole. J Bacteriol. 1995 Mar;177(6):1461–1469. doi: 10.1128/jb.177.6.1461-1469.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Chen P., Andersson D. I., Roth J. R. The control region of the pdu/cob regulon in Salmonella typhimurium. J Bacteriol. 1994 Sep;176(17):5474–5482. doi: 10.1128/jb.176.17.5474-5482.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Elliott T., Roth J. R. Characterization of Tn10d-Cam: a transposition-defective Tn10 specifying chloramphenicol resistance. Mol Gen Genet. 1988 Aug;213(2-3):332–338. doi: 10.1007/BF00339599. [DOI] [PubMed] [Google Scholar]
  12. Heller K. B., Lin E. C., Wilson T. H. Substrate specificity and transport properties of the glycerol facilitator of Escherichia coli. J Bacteriol. 1980 Oct;144(1):274–278. doi: 10.1128/jb.144.1.274-278.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Hendrickson W., Schleif R. A dimer of AraC protein contacts three adjacent major groove regions of the araI DNA site. Proc Natl Acad Sci U S A. 1985 May;82(10):3129–3133. doi: 10.1073/pnas.82.10.3129. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Hertz G. Z., Hartzell G. W., 3rd, Stormo G. D. Identification of consensus patterns in unaligned DNA sequences known to be functionally related. Comput Appl Biosci. 1990 Apr;6(2):81–92. doi: 10.1093/bioinformatics/6.2.81. [DOI] [PubMed] [Google Scholar]
  15. Jeter R. M. Cobalamin-dependent 1,2-propanediol utilization by Salmonella typhimurium. J Gen Microbiol. 1990 May;136(5):887–896. doi: 10.1099/00221287-136-5-887. [DOI] [PubMed] [Google Scholar]
  16. Jeter R. M., Olivera B. M., Roth J. R. Salmonella typhimurium synthesizes cobalamin (vitamin B12) de novo under anaerobic growth conditions. J Bacteriol. 1984 Jul;159(1):206–213. doi: 10.1128/jb.159.1.206-213.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Jeter R. M., Roth J. R. Cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium. J Bacteriol. 1987 Jul;169(7):3189–3198. doi: 10.1128/jb.169.7.3189-3198.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Kleckner N. DNA sequence analysis of Tn10 insertions: origin and role of 9 bp flanking repetitions during Tn10 translocation. Cell. 1979 Apr;16(4):711–720. doi: 10.1016/0092-8674(79)90087-4. [DOI] [PubMed] [Google Scholar]
  19. Kleckner N., Steele D. A., Reichardt K., Botstein D. Specificity of insertion by the translocatable tetracycline-resistance element Tn10. Genetics. 1979 Aug;92(4):1023–1040. doi: 10.1093/genetics/92.4.1023. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Reeder T., Schleif R. AraC protein can activate transcription from only one position and when pointed in only one direction. J Mol Biol. 1993 May 20;231(2):205–218. doi: 10.1006/jmbi.1993.1276. [DOI] [PubMed] [Google Scholar]
  21. Richter-Dahlfors A. A., Andersson D. I. Analysis of an anaerobically induced promoter for the cobalamin biosynthetic genes in Salmonella typhimurium. Mol Microbiol. 1991 Jun;5(6):1337–1345. doi: 10.1111/j.1365-2958.1991.tb00780.x. [DOI] [PubMed] [Google Scholar]
  22. Rondon M. R., Escalante-Semerena J. C. The poc locus is required for 1,2-propanediol-dependent transcription of the cobalamin biosynthetic (cob) and propanediol utilization (pdu) genes of Salmonella typhimurium. J Bacteriol. 1992 Apr;174(7):2267–2272. doi: 10.1128/jb.174.7.2267-2272.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Roth J. R., Lawrence J. G., Rubenfield M., Kieffer-Higgins S., Church G. M. Characterization of the cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium. J Bacteriol. 1993 Jun;175(11):3303–3316. doi: 10.1128/jb.175.11.3303-3316.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Schmieger H. A method for detection of phage mutants with altered transducing ability. Mol Gen Genet. 1971;110(4):378–381. doi: 10.1007/BF00438281. [DOI] [PubMed] [Google Scholar]
  25. Stirling D. A., Hulton C. S., Waddell L., Park S. F., Stewart G. S., Booth I. R., Higgins C. F. Molecular characterization of the proU loci of Salmonella typhimurium and Escherichia coli encoding osmoregulated glycine betaine transport systems. Mol Microbiol. 1989 Aug;3(8):1025–1038. doi: 10.1111/j.1365-2958.1989.tb00253.x. [DOI] [PubMed] [Google Scholar]
  26. Stormo G. D. Consensus patterns in DNA. Methods Enzymol. 1990;183:211–221. doi: 10.1016/0076-6879(90)83015-2. [DOI] [PubMed] [Google Scholar]
  27. Sweet G., Gandor C., Voegele R., Wittekindt N., Beuerle J., Truniger V., Lin E. C., Boos W. Glycerol facilitator of Escherichia coli: cloning of glpF and identification of the glpF product. J Bacteriol. 1990 Jan;172(1):424–430. doi: 10.1128/jb.172.1.424-430.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Toraya T., Honda S., Fukui S. Fermentation of 1,2-propanediol with 1,2-ethanediol by some genera of Enterobacteriaceae, involving coenzyme B12-dependent diol dehydratase. J Bacteriol. 1979 Jul;139(1):39–47. doi: 10.1128/jb.139.1.39-47.1979. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Way J. C., Davis M. A., Morisato D., Roberts D. E., Kleckner N. New Tn10 derivatives for transposon mutagenesis and for construction of lacZ operon fusions by transposition. Gene. 1984 Dec;32(3):369–379. doi: 10.1016/0378-1119(84)90012-x. [DOI] [PubMed] [Google Scholar]

Articles from Journal of Bacteriology are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES