Functional divergence in the glutathione transferase superfamily in plants -: Identification of two classes with putative functions in redox homeostasis in Arabidopsis thaliana

被引:318
作者
Dixon, DP
Davis, BG
Edwards, R [1 ]
机构
[1] Univ Durham, Sch Biol & Biomed Sci, Durham DH1 3LE, England
[2] Univ Oxford, Dyson Perrins Lab, Dept Chem, Oxford OX1 3QY, England
基金
英国生物技术与生命科学研究理事会;
关键词
D O I
10.1074/jbc.M202919200
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Searches with the human Omega glutathione transferase (GST) identified two outlying groups of the GST superfamily in Arabidopsis thaliana which differed from all other plant GSTs by containing a cysteine in place of a serine at the active site. One group consisted of four genes, three of which encoded active glutathione-dependent dehydroascorbate reductases (DHARs). Two DHARs were predicted to be cytosolic, whereas the other contained a chloroplast targeting peptide. The DELARs were also active as thiol transferases but had no glutathione conjugating activity. Unlike most other GSTs, DHARs were monomeric. The other class of GST comprised two genes termed the Lambda GSTs (GSTLs). The recombinant GSTLs were also monomeric and had glutathione-dependent thiol transferase activity. One GSTL was cytosolic, whereas the other was chloroplast-targeted. When incubated with oxidized glutathione, the putative active site cysteine of the GSTLs and cytosolic DHARs formed mixed disulfides with glutathione, whereas the plastidic DHAR formed an intramolecular disulfide. DHAR S-glutathionylation was consistent with a proposed catalytic mechanism for dehydroascorbate reduction. Roles for the cytosolic DHARs and GSTLs as antioxidant enzymes were also inferred from the induction of the respective genes following exposure to chemicals and oxidative stress.
引用
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页码:30859 / 30869
页数:11
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