Abstract
Cystathionine γ-synthase (CGS) catalyzes the first committed step of Met biosynthesis. We have shown that expression of the CGS gene is feedback-regulated at the level of mRNA stability in response to Met or its metabolite in Arabidopsis, and that the amino acid sequence encoded by the first exon of the CGS gene itself is responsible for the regulation. Since the exon 1 polypeptide acts in cis, we have proposed that the regulation occurs during translation when the nascent polypeptide and its mRNA are in close proximity. The in vitro translation system of wheat germ was used to analyze decay intermediates of CGS mRNA. Furthermore, from the CGS exon 1 deletion analysis of reporter activity using in vitro translation system, it has been shown that the conserved region is important for the regulation. To gain additional insight of decay intermediates of CGS mRNA, Northern blot analysis of deletion constructs is underway.
