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植物叶绿体基因组全结构的阐明,已充分揭示该遗传体系兼有原核生物和真核生物基因组的特征。在叶绿体基因中,除存在一些内含子结构外,还具有像rpl12这样复杂的分割式基因。同时,不同基因的转录速度也存在着显著的差异。这些都意味着叶绿体基因在转录后必然有着复杂的剪接加工过程。RNA结合蛋白是一类在RNA加工中起重要作用的蛋白。Li等首次从烟草叶绿体中分离到与RNA转录直接相关的RNA结合蛋白,并且证明它们是由细胞核编码,在细胞质中合成后再输入到叶绿体中去的。至今,已从烟草、菠菜以及拟南芥菜等植物中发现了约10种核编码的叶绿体RNA结合蛋白,它们有类似的构造特征。我们从水稻cDNA文库中首次筛选到一个RNA结合蛋白(cp28)的基因,其相应的肽链由264个氨基酸组成。和其他叶绿体RNA结合蛋白相仿,它也包含有两个RNA结合结构域(称为consensus sequence-type RNA-binding domain,即CS-RBD),其中各含有一个由8个氨基酸组成的高度保守的一致顺序(ribonucleoprotein consensus sequence,即RNP-CS)。N端区域的传送肽(穿膜信号肽)由60个氨基酸组成,其后是一段负电荷十分集中的酸性肽段,但传送肽和酸性肽段的氨基酸顺序与其他植物的RNA结合蛋白的同源性很低。根据全长肽链的同源性比较,我们还分析了水稻cp28
The elucidation of plant chloroplast genome structure has fully revealed that the genetic system has the characteristics of both prokaryotes and eukaryotic genomes. Among the chloroplast genes, there are some complicated segregation genes like rpl12 in addition to some intron structure. At the same time, there are also significant differences in the transcriptional rates of different genes. All of these mean that the chloroplast gene must have a complex splicing process after transcription. RNA-binding proteins are a class of proteins that play an important role in RNA processing. For the first time, Li et al. Isolated RNA-binding proteins directly related to RNA transcription from tobacco chloroplasts and demonstrated that they are encoded by the nucleus and synthesized in the cytoplasm before they are introduced into the chloroplast. To date, about 10 nuclear-encoded chloroplast RNA-binding proteins have been found from plants such as tobacco, spinach, and Arabidopsis thaliana and have similar structural features. We first screened out a rice RNA-binding protein (cp28) gene from a rice cDNA library, with the corresponding peptide chain consisting of 264 amino acids. Similar to other chloroplast RNA binding proteins, it also contains two RNA-binding domains known as consensus sequence-type RNA-binding domains (CS-RBDs), each containing a highly conserved consensus of eight amino acids Sequence (ribonucleoprotein consensus sequence, RNP-CS). The N-terminal region of the transport peptide (the transmembrane signal peptide) consists of 60 amino acids, followed by a section of very negatively charged acidic peptide, but the amino acid sequence of the transport peptide and acidic peptide is identical to that of other plant RNA binding proteins Low source. We also analyzed rice cp28 based on the homology of full-length peptide chains