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 Voulgaris, J.
Right arrow Articles by Squires, C. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Voulgaris, J.
Right arrow Articles by Squires, C. L.

 Previous Article  |  Next Article 

Journal of Bacteriology, July 1999, p. 4170-4175, Vol. 181, No. 14
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.

Increased rrn Gene Dosage Causes Intermittent Transcription of rRNA in Escherichia coli

Justina Voulgaris,1 Sarah French,2 Richard L. Gourse,3 Craig Squires,4 and Catherine L. Squires4,*

Department of Biological Sciences, Columbia University, New York, New York 100271; Department of Microbiology, University of Virginia, Charlottesville, Virginia 229082; Department of Bacteriology, University of Wisconsin, Madison, Wisconsin 537063; and Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 021114

Received 11 February 1999/Accepted 5 May 1999

When the number of rRNA (rrn) operons in an Escherichia coli cells is increased by adding an rrn operon on a multicopy plasmid, the rate of rRNA expression per operon is reduced to maintain a constant concentration of rRNA in the cell. We have used electron microscopy to examine rRNA transcription in cells containing a multicopy plasmid carrying rrnB. We found that there were fewer RNA polymerase molecules transcribing the rrn genes, as predicted from previous gene dosage studies. Furthermore, RNA polymerase molecules were arranged in irregularly spaced groups along the operon. No apparent pause or transcription termination sites that would account for the irregular spacing of the groups of polymerase molecules were observed. We also found that the overall transcription elongation rate was unchanged when the rrn gene dosage was increased. Our data suggest that when rrn gene dosage is increased, initiation events, or promoter-proximal elongation events, are interrupted at irregular time intervals.

* Corresponding author. Mailing address: Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111. Phone: (617) 636-6947. Fax: (617) 636-0337. E-mail: csquires_rib{at}opal.tufts.edu.

Journal of Bacteriology, July 1999, p. 4170-4175, Vol. 181, No. 14
0021-9193/99/$04.00+0
Copyright © 1999, 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 © 1999 by the American Society for Microbiology. All rights reserved.