Abstract
Serine acetyltransferase (Serat) catalyzes the formation of O-acetyl-serine (OAS) from L-serine and acetyl-CoA, leading to synthesis of cysteine. In the genome of Arabidopsis thaliana, there are five Serat genes. Serat1;1, Serat3;1 and Serat3;2 are localized in cytosol, Serat2;1 is in plastids and Serat2;2 is in mitochondria. The activities of Serat1;1 and Serat3;2 are inhibited by L-cysteine, suggesting both isoforms have important roles in regulation of cysteine biosynthesis. In this study, to elucidate the specific role of each Serat gene, T-DNA knockout mutants in each Serat gene were isolated. Using rosette leaves of 2-week-old and 4-week-old plants, expression analysis by RT-PCR and metabolite profiles were conducted. In all mutants, expressions of targeted Serat genes for knockout mutation were inhibited, but expression levels of other Serat genes were not significantly changed. However, accumulation paterns of OAS, cysteine and glutathione among mutants were different, implying each Serat gene has distinct role.
