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A glutathione responsive rice glyoxalase II , Os GLYII ‐2, functions in salinity adaptation by maintaining better photosynthesis efficiency and anti‐oxidant pool
Author(s) -
Ghosh Ajit,
Pareek Ashwani,
Sopory Sudhir K.,
SinglaPareek Sneh L.
Publication year - 2014
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12621
Subject(s) - methylglyoxal , lactoylglutathione lyase , glutathione , chemistry , biochemistry , enzyme , complementation , enzyme kinetics , abiotic stress , mutant , active site , gene
Summary 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, Os GLYII ‐2 was conducted in terms of its metal content, enzyme kinetics and stress tolerance potential. Functional complementation of yeast GLY II mutant (∆ GLO 2) and enzyme kinetics data suggested that Os GLYII ‐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 Os GLYII ‐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 Os GLYII ‐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.