Abstract
Transcription of the nitrogen-regulated nac promoter of Klebsiella aerogenes requires sigma54 RNA polymerase, is activated by the phosphorylated form of the transcription factor nitrogen regulator I (NRI) (NtrC), and is repressed by the product of the nac gene, Nac. Nac protects a large portion of the nac control region, extending from positions -130 to -70, from digestion by DNase I. This site(s) lies immediately upstream from the site at which sigma 54 RNA polymerase binds, is downstream of a high-affinity binding site for the transcriptional activator NRI approximately P, and partially overlaps a low-affinity NRI approximately P-binding site. Binding of Nac to the DNA resulted in bending of the DNA but did not interfere with the binding of sigma 54 RNA polymerase to the promoter or with the binding of NRI approximately P to either the high-affinity site or low-affinity site. Furthermore, transcription assays with various wild-type and mutant templates suggested that Nac did not exclude NRI approximately P from either the low- or high-affinity sites, nor did Nac interfere with the ability of the polymerase to form the open complex when the binding sites for NRI approximately P were moved to different locations upstream from the promoter. Rather, Nac seemed to repress by an antiactivation mechanism in which the interaction of the NRI approximately P, bound at its normal sites, with sigma 54 RNA polymerase, bound to the promoter, was prevented.
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Selected References
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- Bender R. A., Snyder P. M., Bueno R., Quinto M., Magasanik B. Nitrogen regulation system of Klebsiella aerogenes: the nac gene. J Bacteriol. 1983 Oct;156(1):444–446. doi: 10.1128/jb.156.1.444-446.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bender R. A. The role of the NAC protein in the nitrogen regulation of Klebsiella aerogenes. Mol Microbiol. 1991 Nov;5(11):2575–2580. doi: 10.1111/j.1365-2958.1991.tb01965.x. [DOI] [PubMed] [Google Scholar]
- Best E. A., Bender R. A. Cloning of the Klebsiella aerogenes nac gene, which encodes a factor required for nitrogen regulation of the histidine utilization (hut) operons in Salmonella typhimurium. J Bacteriol. 1990 Dec;172(12):7043–7048. doi: 10.1128/jb.172.12.7043-7048.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Claverie-Martin F., Magasanik B. Positive and negative effects of DNA bending on activation of transcription from a distant site. J Mol Biol. 1992 Oct 20;227(4):996–1008. doi: 10.1016/0022-2836(92)90516-m. [DOI] [PubMed] [Google Scholar]
- Claverie-Martin F., Magasanik B. Role of integration host factor in the regulation of the glnHp2 promoter of Escherichia coli. Proc Natl Acad Sci U S A. 1991 Mar 1;88(5):1631–1635. doi: 10.1073/pnas.88.5.1631. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Feng J., Goss T. J., Bender R. A., Ninfa A. J. Activation of transcription initiation from the nac promoter of Klebsiella aerogenes. J Bacteriol. 1995 Oct;177(19):5523–5534. doi: 10.1128/jb.177.19.5523-5534.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kustu S., Santero E., Keener J., Popham D., Weiss D. Expression of sigma 54 (ntrA)-dependent genes is probably united by a common mechanism. Microbiol Rev. 1989 Sep;53(3):367–376. doi: 10.1128/mr.53.3.367-376.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wu H. M., Crothers D. M. The locus of sequence-directed and protein-induced DNA bending. Nature. 1984 Apr 5;308(5959):509–513. doi: 10.1038/308509a0. [DOI] [PubMed] [Google Scholar]