title: A glutathione responsive rice glyoxalase II, OsGLYII-2, functions in salinity adaptation by maintaining better photosynthesis efficiency and anti-oxidant pool.
abstract: Glyoxalase II (GLY II), the second enzyme of glyoxalase pathway that detoxifies cytotoxic metabolite methylglyoxal (MG), belongs to the superfamily of metallo-β-lactamases. Here, detailed analysis of one of the uncharacterized rice glyoxalase II family members, OsGLYII-2 was conducted in terms of its metal content, enzyme kinetics and stress tolerance potential. Functional complementation of yeast GLY II mutant (∆GLO2) and enzyme kinetics data suggested that OsGLYII-2 possesses characteristic GLY II activity using S-lactoylglutathione (SLG) as the substrate. Further, Inductively Coupled Plasma Atomic Emission spectroscopy and modelled structure revealed that OsGLYII-2 contains a binuclear Zn/Fe centre in its active site and chelation studies indicated that these are essential for its activity. Interestingly, reconstitution of chelated enzyme with Zn(2+), and/or Fe(2+) could not reactivate the enzyme, while addition of Co(2+) was able to do so. End product inhibition study provides insight into the kinetics of GLY II enzyme and assigns hitherto unknown function to reduced glutathione (GSH). Ectopic expression of OsGLYII-2 in Escherichia coli and tobacco provides improved tolerance against salinity and dicarbonyl stress indicating towards its role in abiotic stress tolerance. Maintained levels of MG and GSH as well as better photosynthesis rate and reduced oxidative damage in transgenic plants under stress conditions seems to be the possible mechanism facilitating enhanced stress tolerance.
authors.affiliation: Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Ajit
authors.initials: A
authors.lastname: Ghosh
authors.forename: Ashwani
authors.initials: A
authors.lastname: Pareek
authors.forename: Sudhir K
authors.initials: SK
authors.lastname: Sopory
authors.forename: Sneh L
authors.initials: SL
authors.lastname: Singla-Pareek
mesh_terms: D000222:Adaptation, Physiological; D000975:Antioxidants / Q000378:metabolism*; D015870:Gene Expression; D017930:Genes, Reporter; D005978:Glutathione / Q000031:analogs & derivatives / Q000378:metabolism; D008670:Metals / Q000378:metabolism; D008958:Models, Molecular; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D010788:Photosynthesis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011994:Recombinant Proteins; D054712:Salinity; D017422:Sequence Analysis, DNA; D013312:Stress, Physiological; D013869:Thiolester Hydrolases / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D000099301:Hydroxyacylglutathione Hydrolase
chemical_list: D000975:Antioxidants; D005978:Glutathione; D008670:Metals; D010940:Plant Proteins; D011994:Recombinant Proteins; D013869:Thiolester Hydrolases; D000099301:Hydroxyacylglutathione Hydrolase; C013585:S-lactoylglutathione
keywords: Oryza sativa L.; end product inhibition; glutathione; glyoxalase II; salinity stress; stress tolerance; zinc/iron binuclear centre