GlnK facilitates the dynamic regulation of bacterial nitrogen assimilation

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Title: GlnK facilitates the dynamic regulation of bacterial nitrogen assimilation
Authors: Gosztolai, A
Schumacher, J
Behrends, V
Bundy, JG
Heydenreich, F
Bennett, MH
Buck, M
Barahona, M
Item Type: Journal Article
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.
Issue Date: 23-May-2017
Date of Acceptance: 14-Apr-2017
URI: http://hdl.handle.net/10044/1/48138
DOI: https://dx.doi.org/10.1101/127662
ISSN: 1542-0086
Publisher: Biophysical Society
Start Page: 2219
End Page: 2230
Journal / Book Title: Biophysical Journal
Volume: 112
Issue: 10
Copyright Statement: © 2017 Biophysical Society. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).
Sponsor/Funder: Biotechnology and Biological Sciences Research Council (BBSRC)
Engineering & Physical Science Research Council (EPSRC)
Biotechnology and Biological Sciences Research Council (BBSRC)
Engineering & Physical Science Research Council (EPSRC)
Biotechnology and Biological Sciences Research Council (BBSRC)
Funder's Grant Number: BB/G020434/1
EP/I032223/1
BB/L011468/1
EP/N014529/1
BB/N003608/1
Keywords: Science & Technology
Life Sciences & Biomedicine
Biophysics
SIGNAL-TRANSDUCTION PROTEIN
SYNTHETASE ADENYLYLTRANSFERASE ATASE
ESCHERICHIA-COLI
GLUTAMINE-SYNTHETASE
COVALENT MODIFICATION
ALPHA-KETOGLUTARATE
COMPLEX-FORMATION
CASCADE SYSTEM
EC 2.7.7.49
IN-VIVO
q-bio.SC
q-bio.SC
q-bio.QM
Biophysics
02 Physical Sciences
03 Chemical Sciences
06 Biological Sciences
Publication Status: Published
Appears in Collections:Division of Surgery
Mathematics
Applied Mathematics and Mathematical Physics
Faculty of Natural Sciences



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