Distinct physiological roles for the two l-asparaginase isozymes of Escherichia coli

Yogitha N. Srikhanta, John M Atack, Ifor R Beacham, Michael P Jennings

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Escherichia coli expresses two l-asparaginase (EC isozymes: l-asparaginse I, which is a low affinity, cytoplasmic enzyme that is expressed constitutively, and l-asparaginase II, a high affinity periplasmic enzyme that is under complex co-transcriptional regulation by both Fnr and Crp. The distinct localisation and regulation of these enzymes suggest different roles. To define these roles, a set of isogenic mutants was constructed that lacked either or both enzymes. Evidence is provided that l-asparaginase II, in contrast to l-asparaginase I, can be used in the provision of an anaerobic electron acceptor when using a non-fermentable carbon source in the presence of excess nitrogen.

Original languageEnglish
Pages (from-to)362-365
Number of pages4
JournalBiochemical and Biophysical Research Communications
Issue number3
Publication statusPublished - 5 Jul 2013
Externally publishedYes


  • Anaerobic growth
  • Asparaginase
  • Escherichia coli
  • Isozymes

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