Gamma-glutamyl transpeptidase in transgenic tobacco plants. Cellular localization, processing, and biochemical properties.
gamma-Glutamyl transpeptidase (gamma-GT) is a ubiquitous enzyme that catalyzes the first step of glutathione (GSH) degradation in the gamma-glutamyl cycle in mammals. A cDNA encoding an Arabidopsis homolog for gamma-GT was overexpressed in tobacco (Nicotiana tabacum) plants. A high level of the membrane-bound gamma-GT activity was localized outside the cell in transgenic plants. The overproduced enzyme was characterized by a high affinity to GSH and was cleaved post-translationally in two unequal subunits. Thus, Arabidopsis gamma-GT is similar to the mammalian enzymes in enzymatic properties, post-translational processing, and cellular localization, suggesting analogous biological functions as a key enzyme in the catabolism of GSH.
Storozhenko
Sergei
S
Vakgroep Moleculaire Genetica, Departement Plantengenetica, Vlaams Interuniversitair Instituut voor Biotechnologie, Universiteit Gent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium.
Belles-Boix
Enric
E
Babiychuk
Elena
E
Hérouart
Didier
D
Davey
Mark W
MW
Slooten
Luit
L
Van Montagu
Marc
M
Inzé
Dirk
D
Kushnir
Sergei
S
D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D002462:Cell Membrane / Q000201:enzymology; D003001:Cloning, Molecular; D015971:Gene Expression Regulation, Enzymologic; D005978:Glutathione / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008322:Mammals / Q000235:genetics; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D005810:Multigene Family; D018384:Oxidative Stress; D030821:Plants, Genetically Modified; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics; D005723:gamma-Glutamyltransferase / Q000235:genetics / Q000378:metabolism*
D005723:gamma-Glutamyltransferase; D005978:Glutathione