Nitrogen assimilation and global regulation in Escherichia coli

Annu Rev Microbiol. 2003;57:155-76. doi: 10.1146/annurev.micro.57.030502.090820. Epub 2003 May 1.


Nitrogen limitation in Escherichia coli controls the expression of about 100 genes of the nitrogen regulated (Ntr) response, including the ammonia-assimilating glutamine synthetase. Low intracellular glutamine controls the Ntr response through several regulators, whose activities are modulated by a variety of metabolites. Ntr proteins assimilate ammonia, scavenge nitrogen-containing compounds, and appear to integrate ammonia assimilation with other aspects of metabolism, such as polyamine metabolism and glutamate synthesis. The leucine-responsive regulatory protein (Lrp) controls the synthesis of glutamate synthase, which controls the Ntr response, presumably through its effect on intracellular glutamine. Some Ntr proteins inhibit the expression of some Lrp-activated genes. Guanosine tetraphosphate appears to control Lrp synthesis. In summary, a network of interacting global regulators that senses different aspects of metabolism integrates nitrogen assimilation with other metabolic processes.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Ammonia / metabolism*
  • DNA-Binding Proteins / metabolism
  • DNA-Directed RNA Polymerases / metabolism
  • Escherichia coli / enzymology
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial*
  • Glutamate Synthase / metabolism
  • Glutamate-Ammonia Ligase / metabolism
  • Leucine-Responsive Regulatory Protein
  • Nitrogen / metabolism*
  • Nitrogen Fixation / genetics
  • Nitrogen Fixation / physiology*
  • RNA Polymerase Sigma 54
  • Sigma Factor / metabolism
  • Transcription Factors*


  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • Lrp protein, E coli
  • Sigma Factor
  • Transcription Factors
  • rpoN protein, E coli
  • Leucine-Responsive Regulatory Protein
  • Ammonia
  • Glutamate Synthase
  • DNA-Directed RNA Polymerases
  • RNA Polymerase Sigma 54
  • Glutamate-Ammonia Ligase
  • Nitrogen