Poster: Oxidative Stress

Abs # 140: gGlutamyltransferase and glutathione turnover in Arabidopsis

Presenter:	Xiang, Chengbin , chengbin@iastate.edu
Authors	Xiang, Chengbin  (A)   Safaa, Radwan  (A)   Anita, Peterson  (A)   David, Oliver J (A)
Affiliations:	(A): Botany, Iowa State University

g-Glutamyltransferase (GGT) is the only enzyme known that can break the bond between glutamate and cysteine in glutathione (GSH). It is, therefore, essential in GSH turnover. GSH metabolism is essential for amino acid transport in animals by the g-glutamyl cycle. It has been implicated in sulfur transport, detoxification of xenobiotics, and synthesis of g-glutamyl amino acids in plants. We have used genetics and molecular biology approaches to study the role of this enzyme in plants. There are four GGT genes in Arabidopsis. GGT1 is responsible for about 85% of the GGT activity measured. It is expressed uniformly though the plant. GGT2 mRNA is undetectable in all organs except developing siliques where it is expressed at high levels. GGT3 is expressed at moderate levels in all tissues. The T-DNA insertional knockout plants for GGT1 and GGT2 have been obtained. The analyses of these mutants will be presented and the function of the GGT gene family will be discussed.