In vitro transcription/DNA synthesis using isolated organelle-nuclei:Application to the analysis of the mechanisms that regulate organellegenome function

摘要

Plant cells contain two distinct types of DNA-containing organelles, plastids and mitochondria, which are both considered to be descendants of endosymbionts. DNAs of these organelles associate with specific proteins to form compactly organized DNA-protein complexes, referred to as organelle-nuclei (or nucleoids), in which various functions of organelle genomes, such as replication and gene expression (transcription), are performed. An assay of in vitro transcription/DNA synthesis using isolated organelle-nuclei provided us with a suitable system for analysis of the mechanisms that regulate the functions of organelle genomes. In this review, I focus on (1) the concept of organelle-nuclei, (2) construction and characterization of an in vitro transcription/DNA synthesis system using isolated organelle-nuclei, (3) analysis of the transcriptional regulation of plastid gene expression with emphasis on the presence of distinct RNA polymerase activities in the plastids, and (4) analysis of the DNA synthesizing apparatus of the plastids and mitochondria, considering the possible interaction during evolution between the organelles.