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 Johnson, E. P.
Right arrow Articles by Helinski, D. R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Johnson, E. P.
Right arrow Articles by Helinski, D. R.

 Previous Article  |  Next Article 

Journal of Bacteriology, May 2005, p. 3538-3547, Vol. 187, No. 10
0021-9193/05/$08.00+0     doi:10.1128/JB.187.10.3538-3547.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Gyrase Inhibitors and Thymine Starvation Disrupt the Normal Pattern of Plasmid RK2 Localization in Escherichia coli

Erik P. Johnson,{dagger} Shiyin Yao, and Donald R. Helinski*

Center for Molecular Genetics and Division of Biological Sciences, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093-0322

Received 11 November 2004/ Accepted 14 February 2005

Multicopy plasmids in Escherichia coli are not randomly distributed throughout the cell but exist as defined clusters that are localized at the mid-cell, or at the 1/4 and 3/4 cell length positions. To explore the factors that contribute to plasmid clustering and localization, E. coli cells carrying a plasmid RK2 derivative that can be tagged with a green fluorescent protein-LacI fusion protein were subjected to various conditions that interfere with plasmid superhelicity and/or DNA replication. The various treatments included thymine starvation and the addition of the gyrase inhibitors nalidixic acid and novobiocin. In each case, localization of plasmid clusters at the preferred positions was disrupted but the plasmids remained in clusters, suggesting that normal plasmid superhelicity and DNA synthesis in elongating cells are not required for the clustering of individual plasmid molecules. It was also observed that the inhibition of DNA replication by these treatments produced filaments in which the plasmid clusters were confined to one or two nucleoid bodies, which were located near the midline of the filament and were not evenly spaced throughout the filament, as is found in cells treated with cephalexin. Finally, the enhanced yellow fluorescent protein-RarA fusion protein was used to localize the replication complex in individual E. coli cells. Novobiocin and nalidixic acid treatment both resulted in rapid loss of RarA foci. Under these conditions the RK2 plasmid clusters were not disassembled, suggesting that a completely intact replication complex is not required for plasmid clustering.

* Corresponding author. Mailing address: Center for Molecular Genetics and Division of Biological Sciences, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0322. Phone: (858) 534-3638. Fax: (858) 534-0559. E-mail: dhelinski{at}ucsd.edu.

{dagger} Present address: Quest Diagnostics Nichols Institute, 33608 Ortega Highway, San Juan Capistrano, CA 92675.

Journal of Bacteriology, May 2005, p. 3538-3547, Vol. 187, No. 10
0021-9193/05/$08.00+0     doi:10.1128/JB.187.10.3538-3547.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Zaritsky, A., Woldringh, C. L., Einav, M., Alexeeva, S. (2006). Use of thymine limitation and thymine starvation to study bacterial physiology and cytology.. J. Bacteriol. 188: 1667-1679 [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»