Analyses of the Nuclear Genes for Components of the Chloroplast Genetic System

叶绿体遗传系统的组成部分在核基因组和叶绿体基因组中都有编码。本研究的目的是分析其核基因（包括cDNA）的组成。1）我们分离了50 S核糖体亚基，分离了其蛋白质，并测定了其N-末端氨基酸序列。该蛋白与烟草叶绿体DNA中ORF 55的同源性为14 kd，因此将其命名为rp 132。coli L32.2）用ssDNA亲和层析柱从烟草叶绿体裂解液中分离出cp 28、cp 31、cp 33三种蛋白质，并测定了它们的N端氨基酸序列。然后，我们获得了它们的cDNA克隆，确定了它们的DNA序列，并发现在所有三种蛋白质中存在两个RNA结合结构域。体外RNA结合实验表明它们是核糖核蛋白。3）分离烟草叶绿体EF-Tu及其cDNA，并对其进行一级结构分析。叶绿体EF-Tu基因在N.西尔维斯特里斯

The components of the chloroplast genetic system are encoded both in the nuclear and chloroplast genomes. The present purpose is to analyzed the nuclear genes (including cDNAs) for the components.1) We isolated the 50S ribosomal subunit, fractionated its proteins and determined their N-terminal amino acid sequences. The 14 kd protein sequence matched that deduced from ORF55 located in tobacco chloroplast DNA and hence we designated it as rp132 based on its homology to the E. coli L32.2) We isolated three proteins (cp28, cp31, cp33) from a tobacco chloroplast lysate using an ssDNA affinity column and determined their N-terminal amino acid sequences. We then obtained their cDNA clones, determined their DNA sequences and found the presence of two RNA-binding domains in all three proteins. Invitro RNA-binding assays revealed that they are ribonucleoproteins.3) We isolated tobacco chloroplast EF-Tu and its cDNAs, and analyzed their primary structures. There are two distinct genes for chloroplast EF-Tu in N. Sylvestris.