Membranous translation platforms in the chloroplast of Chlamydomonas reinhardtii

We characterized membranes with chloroplast ribosomes during chloroplast development (using the yellow-in-the-dark 1 mutant) and carried out proteomic analyses of two distinct membrane types as translation platforms for chloroplast ribosomes. The results support roles of “low-density membrane” as a platform for preliminary stages of translation and of a denser “chloroplast translation membrane” as a platform for ongoing translation. These roles are based on the proteomes of these membranes, which include proteins in translation, photosystem biogenesis and the biosynthesis of chlorophyll and correlations of their relative levels and the translational status of the chloroplast before, during and after chloroplast differentiation.

我们以黄化暗培养1号突变体（yellow-in-the-dark 1 mutant）为实验材料，对叶绿体发育过程中结合叶绿体核糖体（chloroplast ribosomes）的膜组分进行了表征，并针对作为叶绿体核糖体翻译平台的两种不同膜类型开展了蛋白质组学分析。研究结果显示，‘低密度膜（low-density membrane）’可作为翻译初始阶段的作用平台，而密度更高的‘叶绿体翻译膜（chloroplast translation membrane）’则可作为持续翻译过程的作用平台。上述结论基于两类膜的蛋白质组数据：其蛋白质组包含翻译相关蛋白、光系统生物发生相关蛋白以及叶绿素生物合成相关蛋白，且两类膜蛋白的相对丰度与叶绿体分化前、分化过程中及分化后的翻译状态存在显著相关性。