Abstract
Cystathionine γ-synthase (CGS) catalyzes a key step of methionine (Met) biosynthesis. It has been revealed that the stability of CGS mRNA stability is autoregulated by S-adenosylmethionine, a direct metabolite of Met, and that the CGS exon 1 region is necessary and sufficient for the regulation.
To identify the factors that are involved in the regulation, transgenic plants carrying the CGS exon 1 and GFP gene under the control of CaMV 35S promoter were mutagenized. 9 mutant candidates were isolated that showed high GFP fluorescence even under Met treatment. Endogenous CGS gene expression was also increased in 2 of the candidates. The fact that the expression of both the transgene and the endogenous gene are increased suggests that the candidates are involved in the CGS regulation. To exclude the possibility that the candidates are involved in Met biosynthesis, free amino acid concentrations of the candidate are now under being measured.
