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Crystal structure of the GlnZ-DraG complex reveals a different form of PII-target interaction.
- Source :
-
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2011 Nov 22; Vol. 108 (47), pp. 18972-6. Date of Electronic Publication: 2011 Nov 09. - Publication Year :
- 2011
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Abstract
- Nitrogen metabolism in bacteria and archaea is regulated by a ubiquitous class of proteins belonging to the P(II)family. P(II) proteins act as sensors of cellular nitrogen, carbon, and energy levels, and they control the activities of a wide range of target proteins by protein-protein interaction. The sensing mechanism relies on conformational changes induced by the binding of small molecules to P(II) and also by P(II) posttranslational modifications. In the diazotrophic bacterium Azospirillum brasilense, high levels of extracellular ammonium inactivate the nitrogenase regulatory enzyme DraG by relocalizing it from the cytoplasm to the cell membrane. Membrane localization of DraG occurs through the formation of a ternary complex in which the P(II) protein GlnZ interacts simultaneously with DraG and the ammonia channel AmtB. Here we describe the crystal structure of the GlnZ-DraG complex at 2.1 Å resolution, and confirm the physiological relevance of the structural data by site-directed mutagenesis. In contrast to other known P(II) complexes, the majority of contacts with the target protein do not involve the T-loop region of P(II). Hence this structure identifies a different mode of P(II) interaction with a target protein and demonstrates the potential for P(II) proteins to interact simultaneously with two different targets. A structural model of the AmtB-GlnZ-DraG ternary complex is presented. The results explain how the intracellular levels of ATP, ADP, and 2-oxoglutarate regulate the interaction between these three proteins and how DraG discriminates GlnZ from its close paralogue GlnB.
- Subjects :
- Bacterial Proteins genetics
Bacterial Proteins metabolism
Biological Transport physiology
Cation Transport Proteins metabolism
Cell Membrane metabolism
Crystallization
Multiprotein Complexes genetics
Multiprotein Complexes metabolism
Mutagenesis, Site-Directed
Nitrogenase metabolism
PII Nitrogen Regulatory Proteins genetics
PII Nitrogen Regulatory Proteins metabolism
Quaternary Ammonium Compounds metabolism
Azospirillum brasilense enzymology
Bacterial Proteins chemistry
Models, Molecular
Multiprotein Complexes chemistry
Nitrogen metabolism
PII Nitrogen Regulatory Proteins chemistry
Protein Conformation
Subjects
Details
- Language :
- English
- ISSN :
- 1091-6490
- Volume :
- 108
- Issue :
- 47
- Database :
- MEDLINE
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Publication Type :
- Academic Journal
- Accession number :
- 22074780
- Full Text :
- https://doi.org/10.1073/pnas.1108038108