Modeling the role of covalent enzyme modification in Escherichia coli nitrogen metabolism

Philip B. Kidd, Ned S. Wingreen

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

In the bacterium Escherichia coli, the enzyme glutamine synthetase (GS) converts ammonium into the amino acid glutamine. GS is principally active when the cell is experiencing nitrogen limitation, and its activity is regulated by a bicyclic covalent modification cascade. The advantages of this bicyclic-cascade architecture are poorly understood. We analyze a simple model of the GS cascade in comparison to other regulatory schemes and conclude that the bicyclic cascade is suboptimal for maintaining metabolic homeostasis of the free glutamine pool. Instead, we argue that the lag inherent in the covalent modification of GS slows the response to an ammonium shock and thereby allows GS to transiently detoxify the cell, while maintaining homeostasis over longer times.

Original languageEnglish (US)
Article number016006
JournalPhysical Biology
Volume7
Issue number1
DOIs
StatePublished - 2010

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Structural Biology
  • Molecular Biology
  • Cell Biology

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