A Model System for Analyzing the Generation of Linear Satellite RNAs

小的感染性RNA，如卫星和类病毒，可以干扰植物细胞中基本但尚未确定的分子过程。最近，许多注意力集中在成熟形式的环状小感染性RNA的产生上。一些卫星和类病毒发生自我裂解反应，而另一些只在核提取物存在的情况下进行切割反应，这一发现增加了我们对RNA分子多功能特性的基本理解。为了研究线性卫星RNA的产生，萝卜皱缩病毒卫星系统是理想的，因为有多个相关卫星，体外改变的卫星的感染性，以及最近发现的正常单体卫星积累所必需的区域。通过在体外改变卫星序列，然后在体外转录侵染的cRNA和接种植物，将准确地鉴定该地区以及其他地区参与卫星加工的核苷酸。为了更好地理解这一潜在的新的处理机制，处理过程中涉及的序列将被复制、删除并移动到卫星分子中的不同位置。为了帮助数据分析，将开发一个体外处理系统，使用受感染和未受感染植物的提取物。小致病RNA的研究是植物生物学中一个特别具有挑战性和耐人寻味的领域。尽管这些RNA可以用分子术语来描述，但它们的作用模式仍然没有解决。它们可以对植物发育产生重大影响的事实表明，这些简单的致病RNA必须以某种方式与正常植物细胞中的基本分子机制相互作用和干扰。

Small infectious RNAs, such as satellites and viroids, can interfere with fundamental but as yet unidentified molecular processes in plant cells. Much attention has been focused recently on the generation of mature forms of circular small infectious RNAs. The discovery that some satellites and viroids undergo self-cleavage reactions while others only process in the presence of nuclear extracts is increasing our basic understanding of the multifunctional properties of RNA molecules. To study the generation of linear satellite RNAs, the turnip crinkle virus satellite system is ideal because of the multiple related satellites, the infectivity of in vitro altered satellite and the recent identification of a region essential for normal monomeric satellite accumulation. By in vitro alteration of the satellite sequence, followed by in vitro transcription of infectious cRNA and inoculation in plants, the nucleotides involved in satellite processing in this region as well as others will be precisely identified. To better understand this potentially novel processing mechanism, sequences involved in processing will be duplicated, deleted and moved to different locations in the satellite molecule. To aid in data analysis, an in vitro processing system will be developed using extracts from infected and uninfected plants. The study of small pathogenic RNAs is a particularly challenging and intriguing area of plant biology. Even though these RNAs can be described in molecular terms, their mode of action remains unsolved. The fact that they can have significant effects on plant development suggests that these simple pathogenic RNAs must somehow interact and interfere with fundamental molecular mechanisms in the normal plant cell.