Compensatory expression and substrate inducibility of gamma-glutamyl transferase GGT2 isoform in Arabidopsis thaliana.
J Exp Bot
; 62(2): 805-14, 2011 Jan.
Article
en En
| MEDLINE
| ID: mdl-20959624
γ-Glutamyl transferases (GGT; EC 2.3.2.2) are glutathione-degrading enzymes that are represented in Arabidopsis thaliana by a small gene family of four members. Two isoforms, GGT1 and GGT2, are apoplastic, sharing broad similarities in their amino acid sequences, but they are differently expressed in the tissues: GGT1 is expressed in roots, leaves, and siliques, while GGT2 was thought to be expressed only in siliques. It is demonstrated here that GGT2 is also expressed in wild-type roots, albeit in very small amounts. GGT2 expression is enhanced in ggt1 knockout mutants, suggesting a compensatory effect to restore GGT activity in the root apoplast. Supplementation with 100 µM glutathione (GSH) resulted in the up-regulation of GGT2 gene expression in wild-type and ggt1 knockout roots, and of GGT1 gene expression in wild-type roots. Glutathione recovery was hampered by the GGT inhibitor serine/borate, suggesting a major role for apoplastic GGTs in this process. These findings can explain the ability of ggt1 knockout mutants to retrieve exogenously added glutathione from the growth medium.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Regulación Enzimológica de la Expresión Génica
/
Arabidopsis
/
Gamma-Glutamiltransferasa
/
Glutatión
Idioma:
En
Revista:
J Exp Bot
Asunto de la revista:
BOTANICA
Año:
2011
Tipo del documento:
Article
País de afiliación:
Italia
Pais de publicación:
Reino Unido