Symons R H
Department of Plant Science, Waite Institute, University of Adelaide, Glen Osmond, SA 5064, Australia.
Nucleic Acids Res. 1997 Jul 15;25(14):2683-9. doi: 10.1093/nar/25.14.2683.
The rolling circle replication of small circular plant pathogenic RNAs requires a processing step to convert multimeric intermediates to monomers which are then circularized. Eleven such RNAs are known so far, two are viroids, one is viroid-like and the remainder are satellite RNAs dependent on a helper virus for replication. The processing step is RNA-catalysed in all cases, at least in vitro. All plus forms of these RNAs self-cleave via the hammerhead structure whereas only eight of the minus RNAs self-cleave, five via the hammerhead structure and three via the hairpin structure. There are about 20 other viroids where the processing mechanism has yet to be determined but they are likely candidates for a new type of self-cleavage reaction which is predicted to be conserved in all these viroids. Hepatitis delta RNA is the only circular pathogenic RNA known to self-cleave in the animal kingdom. It is feasible that more single-stranded circular pathogenic RNAs are waiting to be discovered and these could be prospective for new types of self-cleavage reactions.
小型环状植物致病RNA的滚环复制需要一个加工步骤，将多聚体中间体转化为单体，然后将单体环化。到目前为止，已知有11种这样的RNA，其中两种是类病毒，一种是类类病毒，其余的是依赖辅助病毒进行复制的卫星RNA。至少在体外，所有情况下的加工步骤都是由RNA催化的。这些RNA的所有正链形式都通过锤头结构进行自我切割，而只有8种负链RNA进行自我切割，5种通过锤头结构，3种通过发夹结构。还有大约20种其他类病毒，其加工机制尚未确定，但它们很可能是一种新型自我切割反应的候选者，预计这种反应在所有这些类病毒中都是保守的。丁型肝炎RNA是动物界已知的唯一一种能自我切割的环状致病RNA。很可能还有更多单链环状致病RNA有待发现，它们可能成为新型自我切割反应的研究对象。
