JB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Meng, Q.
Right arrow Articles by Switzer, R. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Meng, Q.
Right arrow Articles by Switzer, R. L.

 Previous Article  |  Next Article 

Journal of Bacteriology, October 2001, p. 5513-5522, Vol. 183, No. 19
0021-9193/01/$04.00+0   DOI: 10.1128/JB.183.19.5513-5522.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.

Regulation of Transcription of the Bacillus subtilis pyrG Gene, Encoding Cytidine Triphosphate Synthetase

Qi Meng and Robert L. Switzer*

Department of Biochemistry, University of Illinois, Urbana, Illinois 61801

Received 12 April 2001/Accepted 5 July 2001

The B. subtilis pyrG gene, which encodes CTP synthetase, is located far from the pyrimidine biosynthetic operon on the chromosome and is independently regulated. The pyrG promoter and 5' leader were fused to lacZ and integrated into the chromosomes of several B. subtilis strains having mutations in genes of pyrimidine biosynthesis and salvage. These mutations allowed the intracellular pools of cytidine and uridine nucleotides to be manipulated by the composition of the growth medium. These experiments indicated that pyrG expression is repressed by cytidine nucleotides but is largely independent of uridine nucleotides. The start of pyrG transcription was mapped by primer extension to a position 178 nucleotides upstream of the translation initiation codon. A factor-independent termination hairpin lying between the pyrG promoter and its coding region is essential for regulation of pyrG expression. Primer-extended transcripts were equally abundant in repressed and derepressed cells when the primer bound upstream of the terminator, but they were much less abundant in repressed cells when the primer bound downstream of the terminator. Furthermore, deletion of the terminator from pyrG-lacZ fusions integrated into the chromosome yielded elevated levels of expression that was not repressible by cytidine. We suggest that cytidine repression of pyrG expression is mediated by an antitermination mechanism in which antitermination by a putative trans-acting protein is reduced by elevated levels of cytidine nucleotides. Conservation of sequences and secondary structural elements in the pyrG 5' leaders of several other gram-positive bacteria indicates that their pyrG genes are regulated by a similar mechanism.

* Corresponding author. Mailing address: Department of Biochemistry, University of Illinois, 600 South Mathews Ave., Urbana, IL 61801. Phone: (217) 333-3940. Fax: (217) 244-5858. E-mail: rswitzer{at}uiuc.edu.

Journal of Bacteriology, October 2001, p. 5513-5522, Vol. 183, No. 19
0021-9193/01/$04.00+0   DOI: 10.1128/JB.183.19.5513-5522.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Appl. Environ. Microbiol. Infect. Immun. Eukaryot. Cell
Mol. Cell. Biol. J. Virol. Microbiol. Mol. Biol. Rev.
ALL ASM JOURNALS

Copyright © 2001 by the American Society for Microbiology. All rights reserved.