MECHANISM OF PROTEIN TRANSPORT INTO CHLOROPLASTS

这项研究的长期目标是深入了解选择性 将蛋白质从细胞质运输到专门的细胞器。 这 工作将集中于将蛋白质输入叶绿体。 的 叶绿体是真核生物中两种产生能量的细胞器之一。 像蛋白质一样，它的大多数蛋白质都是由核编码的。 基因组，作为前体合成，并通过膜运输 组装前的屏障。 目前的拨款将调查这些信号 用于选择性地将蛋白质靶向一个细胞器，并将决定 细胞器特异性蛋白质是如何定位在 进口后的车厢 分离的小麦基因编码两个重要的叶绿体蛋白， 捕光复合物叶绿素a/B结合蛋白 和核酮糖1，5-二磷酸羧化酶（rbcS）的小亚基， 通过重组DNA方法（即定点突变）进行修饰。 在 在无细胞系统中，重组蛋白将被合成并孵育 用离体叶绿体研究对输入的影响。 这 这种方法提供了一种在叶绿体装配中获得突变体的方法， 然而这是通过传统遗传学实现的。 这些研究将导致 了解用于在蛋白质中路由蛋白质的一般原理， cell. 最终，将任何修饰的蛋白质靶向于 特异性细胞器。 这项研究可能与 纠正代谢紊乱

The long range goal of this research is to gain insight into the selective transport of proteins from the cytoplasm into specialized organelles. This work will focus on the import of proteins into the chloroplast. The chloroplast is one of the two energy producing organelles in eucaryotes. Like the mitochondrion, most of its proteins are encoded by the nuclear genome, synthesized as precursors, and transported across a membrane barrier before assembly. The current grant will investigate the signals used to selectively target proteins to one organelle, and will determine how the organelle-specific proteins are localized in the correct compartment after import. Isolated wheat genes coding for two important chloroplast proteins, the chlorophyll a/b binding protein of the light harvesting complex (cabLHC) and the small subunit of ribulose 1,5-bisphosphate carboxylase (rbcS), will be modified by recombinant DNA methods, i.e. site-directed mutagenesis. In a cell-free system, restructured proteins will be synthesized and incubated with isolated chloroplasts to investigate the effects on import. This approach provides a means of obtaining mutants in chloroplast assembly not yet achieved by conventional genetics. These studies will lead to an understanding of the general principles used to route proteins in the cell. Eventually it should be possible to target any modified protein to a specific cytoplasmic organelle. This research may have relevance to correcting metabolic disorders.