Abstract
The plastid has its own semi-autonomous genetic system. It has been known the expression of plastid genes depends at the translational level, rather than the transcription and the RNA accumulation levels.
The machinery of plastid genetics system is similar to that of prokaryotes, whereas the translation mechanism is distinguished between them. The translation of prokaryotic mRNAs is initiated through the Shine-Dalgarno (SD) sequence of the mRNAs. The tobacco plastid mRNA is comprised of 79 species, but, two-thirds of them do not contain SD-like sequences at a proper position. A question is what mechanism operates for the plastid mRNA translation.
We have characterized the translational level by our tobacco chloroplast DNA microarray with total RNA and polysome-associated RNA (translationally activated mRNA) isolated from tobacco plants. Then, conserved sequences within the 5' and 3' UTRs have been identified. We discuss possible translation mechanisms for plastid mRNAs.
