1887

Abstract

The regulator of fumarate and nitrate reduction (FNR) protein of is an oxygen-responsive transcription regulator that acts mainly to activate the transcription of genes associated with anaerobic energy generation during periods of oxygen starvation. The gene of the swine pathogen encodes an FNR homologue, HlyX, which can complement the anaerobic respiratory deficiencies of an mutant. However, FNR and HlyX have distinct but overlapping regulons because during anaerobic incubation, -expressing K-12 strains produce an otherwise latent haemolysin. The gene encoding the ‘latent’ haemolysin has been designated and analysis of the promoter region by DNase I footprinting reveals the presence of an FNR- (HlyX-) binding site. Anaerobic expression of an reporter was 6.5-fold higher in compared to -expressing cells. Both FNR and HlyX recruited RNA polymerase to the promoter but formed different ternary complexes. One major transcript (tsp1) initiating at 78.5 bp downstream of the FMR-binding site and four minor transcripts initiating at 73.5 (tsp2), 71.5 (tsp3), 63.5 (tsp4) and 62.5 (tsp5) bp from the FNR site were detected. From the position of the FNR box relative to the transcript starts, is expressed from a Class I FNR-regulated promoter. Substitution of selected FNR amino acids with the residues found in the equivalent positions in HlyX indicated that Activating Region 1 (AR1) of FNR forms a surface encompassing β to β and that the AR1 contact at Class I promoters is different to that at Class II promoters, although the same surface is involved. The FNR variant, FNR-A225T, combined the properties of FNR (good activation from Class II promoters) and HlyX (good activation of Class I promoters) and conferred the haemolytic phenotype.

Keyword(s): Class I promoter , FNR , haemolysin , HlyE and HlyX
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/content/journal/micro/10.1099/00221287-143-12-3785
1997-12-01
2021-04-16
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References

  1. Aiba H., Adhya S., Decrombrugghe B. 1981; Evidence for two functional gal promoters in intact Escherichia coli cells.. J Biol Chem 256:1905–1910
    [Google Scholar]
  2. Ebright R.H. 1993; Transcription activation at Class I CAP- dependent promoters.. Mol Microbiol 8:797–802
    [Google Scholar]
  3. Gerischer V., Durre P. 1992; Messenger-RNA analysis of the adc gene region of Clostridium acetobutylicum during the shift to solventogenesis.. J Bacterial 174:426–433
    [Google Scholar]
  4. Green J., Baldwin M.L. 1997; HlyX, the FNR homologue of Actinobacillus pleuropneumoniae, is a [4Fe-4S] containing oxygen-responsive transcription regulator that anaerobically activates FNR-dependent Class I promoters via an enhanced AR1 contact.. Mol Microbiol 24:593–605
    [Google Scholar]
  5. Green J., Trageser M., Six S., Unden G., Guest J.R. 1991; Characterization of the FNR protein of Escherichia coli, an iron binding transcriptional regulator.. Proc R Soc Ser B 244137–144
    [Google Scholar]
  6. Green J., Sharrocks A.D., Maclnnes J.I., Guest J.R. 1992; Purification of HlyX, a potential regulator of haemolysin synthesis, and properties of HlyX: FNR hybrids.. Proc R Soc Ser B 24879–84
    [Google Scholar]
  7. Green J., Bennett B., Jordan P., Ralph E.T., Thomson A.J., Guest J.R. 1996a; Reconstitution of the [4Fe-4S] cluster in FNR and demonstration of the aerobic-anaerobic transcription switch in vitro. . Biochem J 316:887–892
    [Google Scholar]
  8. Green J., Irvine A.S., Meng W., Guest J.R. 1996b; FNR-DNA interactions at natural and semi-synthetic promoters.. Mol Microbiol 19:125–137
    [Google Scholar]
  9. Green J., Anjum M.F., Guest J.R. 1996c; The ndh binding protein (Nbp) regulates the ndh gene of Escherichia coli in response to growth phase and is identical to Fis.. Mol Microbiol 20:1043–1055
    [Google Scholar]
  10. Guest J.R., Green J., Irvine A.S., Spiro S. 1996; The FNR modulon and FNR-regulated gene expression.. In Regulation and Gene Expression in Escherichia coli pp. 317–342 Edited by Lin E. C. C., Lynch A. S. Austin, TX: R. G. Landes & Co.;
    [Google Scholar]
  11. Lazazzera B.A., Beinert H., Khoroshilova N., Kennedy M.C., Kiley P.J. 1996; DNA-binding and dimerization of the Fe-S containing FNR protein of Escherichia coli are regulated by oxygen.. J Biol Chem 271:2762–2768
    [Google Scholar]
  12. Maclnnes J.I., Kim J.E., Lian C.-J., Soltes G.A. 1990; Actinobacillus pleuropneumoniae hlyX gene homology with the fnr gene of Escherichia coli. . J Bacteriol 172:4587–4592
    [Google Scholar]
  13. Maxam A. M., Gilbert W. 1980; Sequencing end-labelled DNA with base-specific chemical cleavages.. Methods Enzymol 65:499–560
    [Google Scholar]
  14. Miller J.H. 1972 Experiments in Molecular Genetics Cold Spring Harbor, NY: Cold Spring Harbor Laboratory;
    [Google Scholar]
  15. Niu W., Zhou Y., Dong Q., Ebright Y., Ebright R.H. 1994; Characterisation of the activating region of Escherichia coli catabolite gene activator protein (CAP). I. Saturation and alanine-scanning mutagenesis.. J Mol Biol 243:595–602
    [Google Scholar]
  16. Niu W., Kim Y., Tau G., Heyduk T., Ebright R.H. 1996; Transcription activation at Class II CAP-dependent promoters: two interactions between CAP and RNA polymerase.. Cell 87:1123–1134
    [Google Scholar]
  17. Oscarsson J., Mizunoe Y., Uhlin B.E., Haydon D.J. 1996; Induction of haemolytic activity in Escherichia coli by the sly A gene product.. Mol Microbiol 20:191–199
    [Google Scholar]
  18. Ramos H.C., Boursier L., Moszer I., Kunst F., Danchin A., Glaser P. 1995; Anaerobic transcription activation in Bacillus subtilis: identification of distinct FNR-dependent and -inde-pendent regulatory mechanisms.. EMBO J 14:5984–5994
    [Google Scholar]
  19. Savery N., Rhodius V., Busby S. 1996; Protein-protein interactions during transcription activation: the case of the Escherichia coli cyclic AMP receptor protein.. Philos Trans R Soc Lond B Biol Sci 351:543–550
    [Google Scholar]
  20. Spiro S., Guest J.R. 1987; Regulation and overexpression of the fnr gene of Escherichia coli. . J Gen Microbiol 133:3279–3288
    [Google Scholar]
  21. Wing H.J., Williams S.M., Busby S.J.W. 1995; Spacing requirements for transcription activation by Escherichia coli FNR protein.. J Bacteriol 177:6704–6710
    [Google Scholar]
  22. Zhou Y., Merkel T., Ebright R.H. 1994; Characterization of the activating region of Escherichia coli catabolite gene activator protein (CAP). II. Role at Class I and Class II CAP-dependent promoters.. J Mol Biol 243:603–610
    [Google Scholar]
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