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 Van Dommelen, A.
Right arrow Articles by de Zamaroczy, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Van Dommelen, A.
Right arrow Articles by de Zamaroczy, M.

J Bacteriol, May 1998, p. 2652-2659, Vol. 180, No. 10
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.

(Methyl)ammonium Transport in the Nitrogen-Fixing Bacterium Azospirillum brasilense

Anne Van Dommelen,1 Veerle Keijers,1 Jos Vanderleyden,1,* and Miklos de Zamaroczy2

F. A. Janssens Laboratory of Genetics, 3001 Heverlee, Belgium,1 and Unité de Physiologie Cellulaire, Département des Biotechnologies, Institut Pasteur, 75724 Paris Cedex 15, France2

Received 12 November 1997/Accepted 23 February 1998

An ammonium transporter of Azospirillum brasilense was characterized. In contrast to most previously reported putative prokaryotic NH4+ transporter genes, A. brasilense amtB is not part of an operon with glnB or glnZ which, in A. brasilense, encode nitrogen regulatory proteins PII and PZ, respectively. Sequence analysis predicts the presence of 12 transmembrane domains in the deduced AmtB protein and classifies AmtB as an integral membrane protein. Nitrogen regulates the transcription of the amtB gene in A. brasilense by the Ntr system. amtB is the first gene identified in A. brasilense whose expression is regulated by NtrC. The observation that ammonium uptake is still possible in mutants lacking the AmtB protein suggests the presence of a second NH4+ transport mechanism. Growth of amtB mutants at low ammonium concentrations is reduced compared to that of the wild type. This suggests that AmtB has a role in scavenging ammonium at low concentrations.

* Corresponding author. Mailing address: F. A. Janssens Laboratory of Genetics, KU Leuven, K. Mercierlaan 92, 3001 Heverlee, Belgium. Phone: 32 16 32 96 79. Fax: 32 16 32 19 66. E-mail: Jozef.vanderleyden{at}agr.kuleuven.ac.be.

J Bacteriol, May 1998, p. 2652-2659, Vol. 180, No. 10
0021-9193/98/$04.00+0
Copyright © 1998, 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 © 1998 by the American Society for Microbiology. All rights reserved.