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γ‐Glutamyl transpeptidase GGT4 initiates vacuolar degradation of glutathione S ‐conjugates in Arabidopsis
Author(s) -
Grzam Anke,
Martin Melinda N.,
Hell Rüdiger,
Meyer Andreas J.
Publication year - 2007
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.05.071
Subject(s) - glutathione , vacuole , biochemistry , arabidopsis thaliana , cysteine , arabidopsis , chemistry , cytosol , mutant , biology , enzyme , gene , cytoplasm
The xenobiotic monochlorobimane is conjugated to glutathione in the cytosol of Arabidopsis thaliana , transported to the vacuole, and hydrolyzed to cysteine S ‐bimane [Grzam, A., Tennstedt, P., Clemens, S., Hell, R. and Meyer, A.J. (2006) Vacuolar sequestration of glutathione S ‐conjugates outcompetes a possible degradation of the glutathione moiety by phytochelatin synthase. FEBS Lett. 580, 6384–6390]. The work here identifies γ‐glutamyl transpeptidase 4 (At4g29210, GGT4) as the first step of vacuolar degradation of glutathione conjugates. Hydrolysis of glutathione S ‐bimane is blocked in ggt4 null mutants of A. thaliana . Accumulation of glutathione S ‐bimane in mutants and in wild‐type plants treated with the high affinity GGT inhibitor acivicin shows that GGT4 is required to initiate the two step hydrolysis sequence. GGT4:green fluorescent protein fusions were used to demonstrate that GGT4 is localized in the lumen of the vacuole.