title: A nuclear-localized rice glyoxalase I enzyme, OsGLYI-8, functions in the detoxification of methylglyoxal in the nucleus.
abstract: The cellular levels of methylglyoxal (MG), a toxic byproduct of glycolysis, rise under various abiotic stresses in plants. Detoxification of MG is primarily through the glyoxalase pathway. The first enzyme of the pathway, glyoxalase I (GLYI), is a cytosolic metalloenzyme requiring either Ni2+or Zn2+for its activity. Plants possess multiple GLYI genes, of which only some have been partially characterized; hence, the precise molecular mechanism, subcellular localization and physiological relevance of these diverse isoforms remain enigmatic. Here, we report the biochemical properties and physiological role of a putative chloroplast-localized GLYI enzyme, OsGLYI-8, from rice, which is strikingly different from all hitherto studied GLYI enzymes in terms of its intracellular localization, metal dependency and kinetics. In contrast to its predicted localization, OsGLYI-8 was found to localize in the nucleus along with its substrate, MG. Further, OsGLYI-8 does not show a strict requirement for metal ions for its activity, is functional as a dimer and exhibits unusual biphasic steady-state kinetics with a low-affinity and a high-affinity substrate-binding component. Loss of AtGLYI-2, the closest Arabidopsis ortholog of OsGLYI-8, results in severe germination defects in the presence of MG and growth retardation under salinity stress conditions. These defects were rescued upon complementation with AtGLYI-2 or OsGLYI-8. Our findings thus provide evidence for the presence of a GLYI enzyme and MG detoxification in the nucleus.
authors: Plant Stress Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.|School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
authors: Charanpreet
authors: C
authors: Kaur
authors: Plant Stress Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors: Amit K
authors: AK
authors: Tripathi
authors: Plant Stress Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors: Kamlesh K
authors: KK
authors: Nutan
authors: Plant Stress Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors: Shweta
authors: S
authors: Sharma
authors: Plant Stress Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors: Ajit
authors: A
authors: Ghosh
authors: School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
authors: Jayant K
authors: JK
authors: Tripathi
authors: School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
authors: Ashwani
authors: A
authors: Pareek
authors: Plant Stress Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors: Sneh L
authors: SL
authors: Singla-Pareek
authors: Plant Stress Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors: Sudhir K
authors: SK
authors: Sopory
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D005816:Genetic Complementation Test; D007700:Kinetics; D007791:Lactoylglutathione Lyase / Q000235:genetics / Q000378:metabolism*; D008670:Metals / Q000378:metabolism; D009154:Mutation; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011765:Pyruvaldehyde / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D008670:Metals; D010940:Plant Proteins; D011765:Pyruvaldehyde; D007791:Lactoylglutathione Lyase
keywords: 
  Arabidopsis thaliana
  ; 
  Oryza sativa
  ; biphasic kinetics; glyoxalase I; metal-stimulated; methylglyoxal detoxification; nucleus