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GlnK Facilitates the Dynamic Regulation of Bacterial Nitrogen Assimilation.
- Source :
-
Biophysical journal [Biophys J] 2017 May 23; Vol. 112 (10), pp. 2219-2230. - Publication Year :
- 2017
-
Abstract
- Ammonium assimilation in Escherichia coli is regulated by two paralogous proteins (GlnB and GlnK), which orchestrate interactions with regulators of gene expression, transport proteins, and metabolic pathways. Yet how they conjointly modulate the activity of glutamine synthetase, the key enzyme for nitrogen assimilation, is poorly understood. We combine experiments and theory to study the dynamic roles of GlnB and GlnK during nitrogen starvation and upshift. We measure time-resolved in vivo concentrations of metabolites, total and posttranslationally modified proteins, and develop a concise biochemical model of GlnB and GlnK that incorporates competition for active and allosteric sites, as well as functional sequestration of GlnK. The model predicts the responses of glutamine synthetase, GlnB, and GlnK under time-varying external ammonium level in the wild-type and two genetic knock-outs. Our results show that GlnK is tightly regulated under nitrogen-rich conditions, yet it is expressed during ammonium run-out and starvation. This suggests a role for GlnK as a buffer of nitrogen shock after starvation, and provides a further functional link between nitrogen and carbon metabolisms.<br /> (Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.)
- Subjects :
- Algorithms
Ammonium Compounds metabolism
Cation Transport Proteins metabolism
Escherichia coli
Escherichia coli Proteins genetics
Gene Knockout Techniques
Models, Biological
Nitrogen deficiency
Nucleotidyltransferases genetics
PII Nitrogen Regulatory Proteins genetics
Stress, Physiological
Escherichia coli Proteins metabolism
Nitrogen metabolism
Nucleotidyltransferases metabolism
PII Nitrogen Regulatory Proteins metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1542-0086
- Volume :
- 112
- Issue :
- 10
- Database :
- MEDLINE
- Journal :
- Biophysical journal
- Publication Type :
- Academic Journal
- Accession number :
- 28538158
- Full Text :
- https://doi.org/10.1016/j.bpj.2017.04.012