HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Zatyka, M. Articles by Thomas, C. M. Search for Related Content PubMed PubMed Citation Articles by Zatyka, M. Articles by Thomas, C. M. Agricola Articles by Zatyka, M. Articles by Thomas, C. M.

Regulation of transfer genes of promiscuous IncP plasmid RK2: repression of Tra1 region transcription both by relaxosome proteins and by the Tra2 regulator TrbA

Malgorzata Zatyka

School of Biological Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK

Author for correspondence: Chistopher M. Thomas. Tel: + 44 21 414 5903. Fax: +44 21 414 5925.

ABSTRACT

The Tra1 region of broad host range IncP plasmid RK2 encodes proteins essential for its promiscuous conjugative transfer and includes oriT, the site at which nicking occurs to initiate transfer replication. Unregulated expression of the Tra1 region genes would be likely to place a major burden on the host. To investigate the control of these genes the three transcriptional promoters from this region were cloned by PCR and inserted into xylE promoter probe vectors. The strength of traJp and traKp was estimated to be six to eightfold less than the strong trfA promoter which is required for expression of genes for vegetative replication of RK2. The traG promoter was about one-tenth the strength of the other two. These promoters are not repressed by products of the central control operon of RK2. However, traJp and traKp, which are arranged as back to back divergent promoters in the oriT region, are repressed by TraK which constitutes part of the relaxosome necessary for nicking at oriT. A second relaxosome protein, TraJ, represses traJp. traGp is not repressed by any relaxosome proteins. All three promoters are repressed by TrbA, which is encoded at the start of the trb operon containing the rest of the transfer genes (the Tra2 region). These circuits provide: (i) an autoregulatory way of ensuring production of enough relaxosome proteins without overburdening the host; and (ii) a means of coordinating expression of both blocks of transfer genes.

The GenBank accession numbers for the nucleotide sequence data reported in this paper are X54459 and S87583.

On leave of absence from the Department of Microbial Biochemistry, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.

This article has been cited by other articles:

				G. Alonso, K. Baptista, T. Ngo, and D. E. Taylor Transcriptional organization of the temperature-sensitive transfer system from the IncHI1 plasmid R27 Microbiology, November 1, 2005; 151(11): 3563 - 3573. [Abstract] [Full Text] [PDF]

				W. Park, C. O. Jeon, A. M. Hohnstock-Ashe, S. C. Winans, G. J. Zylstra, and E. L. Madsen Identification and Characterization of the Conjugal Transfer Region of the pCg1 plasmid from Naphthalene-Degrading Pseudomonas putida Cg1 Appl. Envir. Microbiol., June 1, 2003; 69(6): 3263 - 3271. [Abstract] [Full Text] [PDF]

				H. Delbruck, G. Ziegelin, E. Lanka, and U. Heinemann An Src Homology 3-like Domain Is Responsible for Dimerization of the Repressor Protein KorB Encoded by the Promiscuous IncP Plasmid RP4 J. Biol. Chem., February 1, 2002; 277(6): 4191 - 4198. [Abstract] [Full Text] [PDF]

				M. Zatyka, L. Bingle, A. C. Jones, and C. M. Thomas Cooperativity between KorB and TrbA Repressors of Broad-Host-Range Plasmid RK2 J. Bacteriol., February 1, 2001; 183(3): 1022 - 1031. [Abstract] [Full Text]