Sugiura M, Hirose T, Sugita M
Center for Gene Research, Nagoya University, Japan.
Annu Rev Genet. 1998;32:437-59. doi: 10.1146/annurev.genet.32.1.437.
The entire sequence (120-190 kb) of chloroplast genomes has been determined from a dozen plant species. The genome contains from 87 to 183 known genes, of which half encode components involved in translation. These include a complete set of rRNAs and about 30 tRNAs, which are likely to be sufficient to support translation in chloroplasts. RNA editing (mostly C to U base changes) occurs in some chloroplast transcripts, creating start and stop codons and changing codons to retain conserved amino acids. Many components that constitute the chloroplast translational machinery are similar to those of Escherichia coli, whereas only one third of the chloroplast mRNAs contain Shine-Dalgarno-like sequences at the correct positions. Analyses conducted in vivo and in vitro have revealed the existence of multiple mechanisms for translational initiation in chloroplasts.
已经测定了十几种植物物种叶绿体基因组的完整序列（120 - 190 kb）。该基因组包含87至183个已知基因，其中一半编码参与翻译的组件。这些组件包括一套完整的rRNA和约30种tRNA，可能足以支持叶绿体中的翻译。RNA编辑（主要是C到U的碱基变化）发生在一些叶绿体转录本中，产生起始和终止密码子，并改变密码子以保留保守氨基酸。构成叶绿体翻译机制的许多组件与大肠杆菌的组件相似，而只有三分之一的叶绿体mRNA在正确位置含有类似Shine - Dalgarno的序列。体内和体外分析揭示了叶绿体中存在多种翻译起始机制。
