Abstract
In vitro systems provide the most significant tool for analyzing the molecular mechanism of gene expression processes including transcription, RNA processing and translation. We have developed an in vitro transcription system from nuclei of tobacco BY-2 cells. This system supports transcription by RNA polymerases I, II and III. This system also supports splicing of pre-tRNAs. Using the system, several features unique to plants have been found. We developed in vitro transcription, RNA editing and translation systems from isolated tobacco chloroplasts. In vitro analysis revealed the existence of a novel promoter motif and of novel mechanisms of translation. In tobacco chloroplast transcripts, C-to-U RNA editing occurs at 34 sites. Using our system, we defined cis-elements of several mRNA editing and found that each editing site is recognized by a unique trans-acting factor. We proposed a novel mechanism for RNA editing.
