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 Madsen, P. L.
Right arrow Articles by Brøndsted, L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Madsen, P. L.
Right arrow Articles by Brøndsted, L.

Journal of Bacteriology, December 1999, p. 7430-7438, Vol. 181, No. 24
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.

The Genetic Switch Regulating Activity of Early Promoters of the Temperate Lactococcal Bacteriophage TP901-1

Peter Lynge Madsen,dagger Annette H. Johansen, Karin Hammer,* and Lone Brøndsted

Department of Microbiology, Technical University of Denmark, DK-2800 Lyngby, Denmark

Received 7 June 1999/Accepted 17 September 1999

A functional analysis of open reading frame 4 (ORF4) and ORF5 from the temperate lactococcal phage TP901-1 was performed by mutant and deletion analysis combined with transcriptional studies of the early phage promoters pR and pL. ORF4 (180 amino acids) was identified as a phage repressor necessary for repression of both promoters. Furthermore, the presence of ORF4 confers immunity of the host strain to TP901-1. ORF5 (72 amino acids) was found to be able to inhibit repression of the lytic promoter pL by ORF4. Upon transformation with a plasmid containing both ORF4 and ORF5 and their cognate promoters, clonal variation is observed: in each transformant, either pL is open and pR is closed or vice versa. The repression is still dependent on ORF4, and the presence of ORF5 is needed for the clonal variation. Induction of a repressed pL fusion containing orf4 and orf5 was obtained by addition of mitomycin C, and the induction was also shown to be dependent on the presence of the RecA protein, even though ORF4 does not contain a recognizable autocleavage site. Our results suggest that the relative amounts of the two proteins ORF4 and ORF5 determine the decision between lytic or lysogenic life cycle after phage infection and that a protein complex consisting of ORF4 and ORF5 may constitute a new type of genetic switch in bacteriophages.

* Corresponding author. Mailing address: Department of Microbiology, Technical University of Denmark, DK-2800 Lyngby, Denmark. Phone: 45 45 25 24 96. Fax: 45 45 88 26 60. E-mail: imkh{at}pop.dtu.dk.

dagger Present address: Carlsberg Laboratory, Department of Yeast Genetics, DK-2500 Valby, Denmark.

Journal of Bacteriology, December 1999, p. 7430-7438, Vol. 181, No. 24
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.