Transcription and translation in chloroplasts

Abstract

Chloroplast gene expression is primarily regulated at the post-transcriptional level, where a variety of complex mechanism have evolved to govern the interaction between the chloroplast and nuclear genomes. These rely on different nuclear-encoded proteins that act on chloroplast mRNAs, including RNA polymerase subunits, RNA stability factors and translational activators. Such control mechanisms must be viewed in the light of the evolutionary heritage of the chloroplast, as an independent unicellular organism. Although some features of prokaryotic gene expression still occur in chloroplasts, their multiple genetic mechanisms for synthesizing RNA and protein are new, and appear to have arisen to provide flexibility of responding to the developmental or environmental state of the plant.