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 Sourjik, V.
Right arrow Articles by Schmitt, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sourjik, V.
Right arrow Articles by Schmitt, R.

Journal of Bacteriology, February 2000, p. 782-788, Vol. 182, No. 3
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

VisN and VisR Are Global Regulators of Chemotaxis, Flagellar, and Motility Genes in Sinorhizobium (Rhizobium) melilotidagger

Victor Sourjik,Dagger Paul Muschler,§ Birgit Scharf, and Rüdiger Schmitt*

Lehrstuhl für Genetik, University of Regensburg, D-93040 Regensburg, Germany

Received 23 August 1999/Accepted 4 November 1999

The known 41 flagellar, chemotaxis, and motility genes of Sinorhizobium (Rhizobium) meliloti contained in the "flagellar regulon" are organized as seven operons and six transcription units that map to a contiguous 45-kb chromosomal region. By probing gene expression on Western blots and with lacZ fusions, we have identified two master regulatory genes, visN and visR, contained in one operon. The gene products probably form a heterodimer, VisNR, acting as a global transcription activator of other flagellar genes. The related 27-kDa VisN and VisR proteins are LuxR-type proteins with typical ligand- and DNA-binding domains. The vis operon itself is constitutively transcribed; however, to activate flagellar genes, VisNR seemingly requires the binding of a yet-unknown effector. Gene expression in tester strains with known deficiencies revealed a hierarchy of three classes of flagellar genes: class I comprises visN and visR; class II, controlled by VisNR, comprises flagellar assembly (class IIA) and motor (class IIB) genes; and class III comprises flagellin and chemotaxis genes that require functional class I and class IIA genes for expression. In contrast to their enterobacterial counterparts, mot genes belong to class II without exerting control over class III genes. While the general hierarchy of gene expression resembles the enterobacterial scheme, the assignment of mot genes to class IIB and the global control by a LuxR-type VisNR activator are new features distinguishing the S. meliloti flagellar gene system.

* Corresponding author. Mailing address: Lehrstuhl für Genetik, University of Regensburg, D-93040 Regensburg, Germany. Phone: 49 (941) 9433162. Fax: 49 (941) 9433163. E-mail: rudy.schmitt{at}biologie.uni-regensburg.de.

dagger Dedicated to Professor Wolfram Heumann on the occasion of his 85th birthday.

Dagger Present address: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138.

§ Present address: Institut für Organische Chemie und Biochemie, Lehrstuhl IV Biotechnologie, Technische Universität München, D-85747 Garching, Germany.

Journal of Bacteriology, February 2000, p. 782-788, Vol. 182, No. 3
0021-9193/00/$04.00+0
Copyright © 2000, 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 © 2000 by the American Society for Microbiology. All rights reserved.