The Role of Cyclophilin CYP20-3 in Activation of Chloroplast Serine Acetyltransferase Under High Light Stress
High light induces the production of cysteine and glutathione (GSH) as part of the oxidative stress response triggered by reactive oxygen species. Cysteine is produced in a two-step process, in which serine acetyltransferase (SAT) catalyses the first reaction. In Arabidopsis thaliana cyclophilin CYP20-3 was reported to promote plastidic SAT1 activity and thus cysteine and GSH production under high light conditions (Dominguez-Solis et al., Proc Natl Acad Sci USA 105:16386–16391, 2008). Challenging the loss of function mutant cyp20-3 with high light however did not reveal any hypersensitivity of the mutant questioning the function of CYP20-3 in regulation of cysteine synthesis. Although physical interaction of CYP20-3 and SAT1 could be confirmed by yeast two-hybrid analysis, plastidic cysteine synthesis induced by oxidative stress is probably regulated by mechanisms other than CYP20-3 function.
KeywordsHigh Light High Light Condition High Light Stress Reactive Oxygen Species Induce Cysteine Synthesis
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