Mechanism of Disruption of the Amt-GlnK Complex by PII-Mediated Sensing of 2-Oxoglutarate

GlnK proteins regulate the active uptake of ammonium by Amt transport proteins by inserting their regulatory T-loops into the transport channels of the Amt trimer and physically blocking substrate passage. They sense the cellular nitrogen status through 2-oxoglutarate, and the energy level of the ce...

Full description

Saved in:
Bibliographic Details
Published in:PloS one 2011-10, Vol.6 (10), p.e26327
Main Authors: Maier, Sarah, Schleberger, Paula, Lü, Wei, Wacker, Tobias, Pflüger, Tobias, Litz, Claudia, Andrade, Susana L. A.
Format: Article
Language:English
Subjects:
Adaptability
Adenosine diphosphate
Ammonium
Arabidopsis thaliana
ATP
Bacillus subtilis
Binding
Biology
Coding
Collaboration
Crystallography
Cyanobacteria
Disruption
E coli
Escherichia coli
Functional analysis
GlnK protein
Hypotheses
Ketoglutaric acid
Metabolism
Nitrates
Nitrogen
PII protein
Proteins
Sensors
Signal transduction
Signaling
Structure-function relationships
Synechococcus elongatus
Transport
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:GlnK proteins regulate the active uptake of ammonium by Amt transport proteins by inserting their regulatory T-loops into the transport channels of the Amt trimer and physically blocking substrate passage. They sense the cellular nitrogen status through 2-oxoglutarate, and the energy level of the cell by binding both ATP and ADP with different affinities. The hyperthermophilic euryarchaeon Archaeoglobus fulgidus possesses three Amt proteins, each encoded in an operon with a GlnK ortholog. One of these proteins, GlnK2 was recently found to be incapable of binding 2-OG, and in order to understand the implications of this finding we conducted a detailed structural and functional analysis of a second GlnK protein from A. fulgidus, GlnK3. Contrary to Af-GlnK2 this protein was able to bind both ATP/2-OG and ADP to yield inactive and functional states, respectively. Due to the thermostable nature of the protein we could observe the exact positioning of the notoriously flexible T-loops and explain the binding behavior of GlnK proteins to their interaction partner, the Amt proteins. A thermodynamic analysis of these binding events using microcalorimetry evaluated by microstate modeling revealed significant differences in binding cooperativity compared to other characterized PII proteins, underlining the diversity and adaptability of this class of regulatory signaling proteins.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0026327