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Ternary complex formation between AmtB, GlnZ and the nitrogenase regulatory enzyme DraG reveals a novel facet of nitrogen regulation in bacteria.
- Source :
-
Molecular microbiology [Mol Microbiol] 2007 Dec; Vol. 66 (6), pp. 1523-35. Date of Electronic Publication: 2007 Nov 19. - Publication Year :
- 2007
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Abstract
- Ammonium movement across biological membranes is facilitated by a class of ubiquitous channel proteins from the Amt/Rh family. Amt proteins have also been implicated in cellular responses to ammonium availability in many organisms. Ammonium sensing by Amt in bacteria is mediated by complex formation with cytosolic proteins of the P(II) family. In this study we have characterized in vitro complex formation between the AmtB and P(II) proteins (GlnB and GlnZ) from the diazotrophic plant-associative bacterium Azospirillum brasilense. AmtB-P(II) complex formation only occurred in the presence of adenine nucleotides and was sensitive to 2-oxoglutarate when Mg(2+) and ATP were present, but not when ATP was substituted by ADP. We have also shown in vitro complex formation between GlnZ and the nitrogenase regulatory enzyme DraG, which was stimulated by ADP. The stoichiometry of this complex was 1:1 (DraG monomer : GlnZ trimer). We have previously reported that in vivo high levels of extracellular ammonium cause DraG to be sequestered to the cell membrane in an AmtB and GlnZ-dependent manner. We now report the reconstitution of a ternary complex involving AmtB, GlnZ and DraG in vitro. Sequestration of a regulatory protein by the membrane-bound AmtB-P(II) complex defines a new regulatory role for Amt proteins in Prokaryotes.
- Subjects :
- Adenosine Diphosphate metabolism
Adenosine Monophosphate metabolism
Azospirillum brasilense enzymology
Azospirillum brasilense genetics
Bacterial Proteins genetics
Cation Transport Proteins genetics
Cation Transport Proteins metabolism
Chromatography, Gel
Electrophoresis, Polyacrylamide Gel
Gene Expression Regulation, Bacterial
Glycoside Hydrolases genetics
Glycoside Hydrolases metabolism
Nitrogenase genetics
Protein Binding
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Azospirillum brasilense metabolism
Bacterial Proteins metabolism
Nitrogen metabolism
Nitrogenase metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0950-382X
- Volume :
- 66
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- Molecular microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 18028310
- Full Text :
- https://doi.org/10.1111/j.1365-2958.2007.06016.x