A unique Ni2+ -dependent and methylglyoxal-inducible rice glyoxalase I possesses a single active site and functions in abiotic stress response

Plant J. 2014 Jun;78(6):951-63. doi: 10.1111/tpj.12521. Epub 2014 May 23.


The glyoxalase system constitutes the major pathway for the detoxification of metabolically produced cytotoxin methylglyoxal (MG) into a non-toxic metabolite D-lactate. Glyoxalase I (GLY I) is an evolutionarily conserved metalloenzyme requiring divalent metal ions for its activity: Zn(2+) in the case of eukaryotes or Ni(2+) for enzymes of prokaryotic origin. Plant GLY I proteins are part of a multimember family; however, not much is known about their physiological function, structure and metal dependency. In this study, we report a unique GLY I (OsGLYI-11.2) from Oryza sativa (rice) that requires Ni(2+) for its activity. Its biochemical, structural and functional characterization revealed it to be a monomeric enzyme, possessing a single Ni(2+) coordination site despite containing two GLY I domains. The requirement of Ni(2+) as a cofactor by an enzyme involved in cellular detoxification suggests an essential role for this otherwise toxic heavy metal in the stress response. Intriguingly, the expression of OsGLYI-11.2 was found to be highly substrate inducible, suggesting an important mode of regulation for its cellular levels. Heterologous expression of OsGLYI-11.2 in Escherichia coli and model plant Nicotiana tabacum (tobacco) resulted in improved adaptation to various abiotic stresses caused by increased scavenging of MG, lower Na(+) /K(+) ratio and maintenance of reduced glutathione levels. Together, our results suggest interesting links between MG cellular levels, its detoxification by GLY I, and Ni(2+) - the heavy metal cofactor of OsGLYI-11.2, in relation to stress response and adaptation in plants.

Keywords: Oryza sativa L; abiotic stresses; glutathione; glyoxalase I; methylglyoxal; nickel-dependent enzyme; stress response; stress tolerance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalytic Domain
  • Escherichia coli / genetics
  • Hydrogen-Ion Concentration
  • Kinetics
  • Lactoylglutathione Lyase / chemistry*
  • Lactoylglutathione Lyase / metabolism
  • Lactoylglutathione Lyase / physiology
  • Models, Molecular
  • Nickel / chemistry*
  • Oryza / genetics
  • Oryza / metabolism*
  • Oryza / physiology
  • Protein Structure, Tertiary
  • Stress, Physiological
  • Tobacco / genetics


  • Nickel
  • Lactoylglutathione Lyase