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 Hinton, D. M.
Right arrow Articles by Mulamba, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hinton, D. M.
Right arrow Articles by Mulamba, R.

 Previous Article  |  Next Article 

Journal of Bacteriology, February 2006, p. 1279-1285, Vol. 188, No. 4
0021-9193/06/$08.00+0     doi:10.1128/JB.188.4.1279-1285.2006

The Bacteriophage T4 Inhibitor and Coactivator AsiA Inhibits Escherichia coli RNA Polymerase More Rapidly in the Absence of {sigma}70 Region 1.1: Evidence that Region 1.1 Stabilizes the Interaction between {sigma}70 and Core

Deborah M. Hinton,* Srilatha Vuthoori,{dagger} and Rebecca Mulamba{ddagger}

Laboratory of Molecular and Cellular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bldg. 8 Room 2A-13, Bethesda, Maryland 20892-0830

Received 7 October 2005/ Accepted 7 December 2005

The N-terminal region (region 1.1) of {sigma}70, the primary {sigma} subunit of Escherichia coli RNA polymerase, is a negatively charged domain that affects the DNA binding properties of {sigma}70 regions 2 and 4. Region 1.1 prevents the interaction of free {sigma}70 with DNA and modulates the formation of stable (open) polymerase/promoter complexes at certain promoters. The bacteriophage T4 AsiA protein is an inhibitor of {sigma}70-dependent transcription from promoters that require an interaction between {sigma}70 region 4 and the –35 DNA element and is the coactivator of transcription at T4 MotA-dependent promoters. Like AsiA, the T4 activator MotA also interacts with {sigma}70 region 4. We have investigated the effect of region 1.1 on AsiA inhibition and MotA/AsiA activation. We show that {sigma}70 region 1.1 is not required for MotA/AsiA activation at the T4 middle promoter PuvsX. However, the rate of AsiA inhibition and of MotA/AsiA activation of polymerase is significantly increased when region 1.1 is missing. We also find that RNA polymerase reconstituted with {sigma}70 that lacks region 1.1 is less stable than polymerase with full-length {sigma}70. Our previous work has demonstrated that the AsiA-inhibited polymerase is formed when AsiA binds to region 4 of free {sigma}70 and then the AsiA/{sigma}70 complex binds to core. Our results suggest that in the absence of region 1.1, there is a shift in the dynamic equilibrium between polymerase holoenzyme and free {sigma}70 plus core, yielding more free {sigma}70 at any given time. Thus, the rate of AsiA inhibition and AsiA/MotA activation increases when RNA polymerase lacks region 1.1 because of the increased availability of free {sigma}70. Previous work has argued both for and against a direct interaction between regions 1.1 and 4. Using an E. coli two-hybrid assay, we do not detect an interaction between these regions. This result supports the idea that the ability of region 1.1 to prevent DNA binding by free {sigma}70 arises through an indirect effect.

* Corresponding author. Mailing address: Laboratory of Molecular and Cellular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bldg. 8 Room 2A-13, Bethesda, MD 20892-0830. Phone: (301) 496-9885. Fax: (301) 402-0053. E-mail: dhinton{at}helix.nih.gov.

{dagger} Present address: Regeneron Pharmaceuticals, Inc., Tarrytown, N.Y.

{ddagger} Present address: Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.

Journal of Bacteriology, February 2006, p. 1279-1285, Vol. 188, No. 4
0021-9193/06/$08.00+0     doi:10.1128/JB.188.4.1279-1285.2006




This article has been cited by other articles:

  • Hook-Barnard, I. G., Hinton, D. M. (2009). The promoter spacer influences transcription initiation via {sigma}70 region 1.1 of Escherichia coli RNA polymerase. Proc. Natl. Acad. Sci. USA 106: 737-742 [Abstract] [Full Text]  
  • Vingadassalom, D., Kolb, A., Mayer, C., Collatz, E., Podglajen, I. (2007). Probing the Importance of Selected Phylum-specific Amino Acids in {sigma}A of Bacteroides fragilis, a Primary {sigma} Factor Naturally Devoid of an N-terminal Acidic Region 1.1. J. Biol. Chem. 282: 3442-3449 [Abstract] [Full Text]  
  • Hook-Barnard, I., Johnson, X. B., Hinton, D. M. (2006). Escherichia coli RNA Polymerase Recognition of a {sigma}70-Dependent Promoter Requiring a -35 DNA Element and an Extended -10 TGn Motif. J. Bacteriol. 188: 8352-8359 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»