Posttranscriptional regulation of Arabidopsis cystathionine γ-synthase: Establishment of in vitro translation system derived from Arabidopsis cell extract

Abstract

Cystathionine γ-synthase (CGS) of Arabidopsis catalyzes the key step of methionine biosynthesis. Expression of the CGS gene is negatively feedback-regulated at the step of mRNA stability in response to S-adenosylmethionine (SAM). The regulation was reproduced in an in vitro translation system of wheat germ extract. Studies using the wheat germ extract revealed that, prior to the CGS mRNA degradation, translational pausing was induced in response to SAM application. In order to further analyze the regulation mechanism, an in vitro system derived from Arabidopsis will make an ideal system. In this study, we developed an in vitro translation system from Arabidopsis callus cultures. As analyzed by reporter assay, the Arabidopsis cell extract system shows translation activity comparable to that of wheat germ extract, and the level of downregulation by SAM was also at the same level as in wheat germ extract.