Cytosolic γ-glutamyl peptidases process glutathione conjugates in the biosynthesis of glucosinolates and camalexin in Arabidopsis

TY - JOUR

T1 - Cytosolic γ-glutamyl peptidases process glutathione conjugates in the biosynthesis of glucosinolates and camalexin in Arabidopsis

AU - Geu Flores, Fernando

AU - Møldrup, Morten Emil

AU - Böttcher, Christoph

AU - Olsen, Carl Erik

AU - Scheel, Dierk

AU - Halkier, Barbara Ann

PY - 2011/6

Y1 - 2011/6

N2 - The defense-related plant metabolites known as glucosinolates play important roles in agriculture, ecology, and human health. Despite an advanced biochemical understanding of the glucosinolate pathway, the source of the reduced sulfur atom in the core glucosinolate structure remains unknown. Recent evidence has pointed toward GSH, which would require further involvement of a GSH conjugate processing enzyme. In this article, we show that an Arabidopsis thaliana mutant impaired in the production of the γ-glutamyl peptidases GGP1 and GGP3 has altered glucosinolate levels and accumulates up to 10 related GSH conjugates. We also show that the double mutant is impaired in the production of camalexin and accumulates high amounts of the camalexin intermediate GS-IAN upon induction. In addition, we demonstrate that the cellular and subcellular localization of GGP1 and GGP3 matches that of known glucosinolate and camalexin enzymes. Finally, we show that the purified recombinant GGPs can metabolize at least nine of the 10 glucosinolate-related GSH conjugates as well as GS-IAN. Our results demonstrate that GSH is the sulfur donor in the biosynthesis of glucosinolates and establish an in vivo function for the only known cytosolic plant g-glutamyl peptidases, namely, the processing of GSH conjugates in the glucosinolate and camalexin pathways.

AB - The defense-related plant metabolites known as glucosinolates play important roles in agriculture, ecology, and human health. Despite an advanced biochemical understanding of the glucosinolate pathway, the source of the reduced sulfur atom in the core glucosinolate structure remains unknown. Recent evidence has pointed toward GSH, which would require further involvement of a GSH conjugate processing enzyme. In this article, we show that an Arabidopsis thaliana mutant impaired in the production of the γ-glutamyl peptidases GGP1 and GGP3 has altered glucosinolate levels and accumulates up to 10 related GSH conjugates. We also show that the double mutant is impaired in the production of camalexin and accumulates high amounts of the camalexin intermediate GS-IAN upon induction. In addition, we demonstrate that the cellular and subcellular localization of GGP1 and GGP3 matches that of known glucosinolate and camalexin enzymes. Finally, we show that the purified recombinant GGPs can metabolize at least nine of the 10 glucosinolate-related GSH conjugates as well as GS-IAN. Our results demonstrate that GSH is the sulfur donor in the biosynthesis of glucosinolates and establish an in vivo function for the only known cytosolic plant g-glutamyl peptidases, namely, the processing of GSH conjugates in the glucosinolate and camalexin pathways.

U2 - 10.1105/tpc.111.083998

DO - 10.1105/tpc.111.083998

M3 - Journal article

SN - 1040-4651

VL - 23

SP - 2456

EP - 2469

JO - The Plant Cell

JF - The Plant Cell

IS - 6

ER -