Catabolic pathway of arginine in Anabaena involves a novel bifunctional enzyme that produces proline from arginine

Mol Microbiol. 2019 Apr;111(4):883-897. doi: 10.1111/mmi.14203. Epub 2019 Feb 25.


Arginine participates widely in metabolic processes. The heterocyst-forming cyanobacterium Anabaena catabolizes arginine to produce proline and glutamate, with concomitant release of ammonium, as major products. Analysis of mutant Anabaena strains showed that this catabolic pathway is the product of two genes, agrE (alr4995) and putA (alr0540). The predicted PutA protein is a conventional, bifunctional proline oxidase that produces glutamate from proline. In contrast, AgrE is a hitherto unrecognized enzyme that contains both an N-terminal α/β propeller domain and a unique C-terminal domain of previously unidentified function. In vitro analysis of the proteins expressed in Escherichia coli or Anabaena showed arginine dihydrolase activity of the N-terminal domain and ornithine cyclodeaminase activity of the C-terminal domain, overall producing proline from arginine. In the diazotrophic filaments of Anabaena, β-aspartyl-arginine dipeptide is transferred from the heterocysts to the vegetative cells, where it is cleaved producing aspartate and arginine. Both agrE and putA were found to be expressed at higher levels in vegetative cells than in heterocysts, implying that arginine is catabolized by the AgrE-PutA pathway mainly in the vegetative cells. Expression in Anabaena of a homolog of the C-terminal domain of AgrE obtained from Methanococcus maripaludis enabled us to identify an archaeal ornithine cyclodeaminase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ammonia-Lyases / genetics
  • Ammonia-Lyases / metabolism*
  • Anabaena / enzymology*
  • Anabaena / genetics
  • Arginine / metabolism*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Gene Expression Regulation, Bacterial
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Metabolic Networks and Pathways
  • Nitrogen Fixation
  • Proline / metabolism*
  • Proline Oxidase / genetics
  • Proline Oxidase / metabolism


  • Bacterial Proteins
  • Membrane Proteins
  • PutA protein, Bacteria
  • Arginine
  • Proline
  • Proline Oxidase
  • Ammonia-Lyases
  • ornithine cyclodeaminase