Abstract
Expression of AtCGS1 is down-regulated at the step of mRNA degradation in response to S-adenosylmethionine. A short amino acid sequence within the first exon coding region of AtCGS1 is important for the regulation. Translation arrest was observed prior to mRNA degradation in the cell-free system of wheat germ extract (WGE), and Trp-93 and Ser-94 were shown to be important for the translation arrest. Trp-93 and Ser-94 are conserved among angiosperms, but not in Physcomitrella patens. PpCGS sequences corresponding to the AtCGS1 exon 1 were used for induction of the post-transcriptional regulation in WGE and transfection of Physcomitrella and Arabidopsis protoplasts. In WGE and transfection with Arabidopsis protoplasts, the regulation of PpCGS is weaker than that of AtCGS1. By contrast, the result is the opposite in Physcomitrella protoplasts. These results suggest that trans-acting factors may be involved in this regulation besides the sequence of CGS.
