Diener T O
Proc Natl Acad Sci U S A. 1986 Jan;83(1):58-62. doi: 10.1073/pnas.83.1.58.
A model is proposed for the processing of oligomeric viroid replication intermediates into monomeric, circular progeny viroids. The model identifies a thermodynamically extremely stable base-paired configuration that partially or completely dimeric, as well as higher, viroid oligomers can assume and postulates that this structure, which involves structural features common to all viroids (the central conserved region and secondary hairpin I), is essential for precise cleavage and ligation. The model explains why recombinant plasmids containing tandem repeats of two or more viroid sequence equivalents are highly infectious when inoculated into viroid-susceptible plants, why certain plasmids containing partially duplicated viroid-specific inserts are less infectious, and why plasmids containing monomeric inserts are noninfectious or at best marginally infectious. The model also accounts for the fact that vector-derived sequences on either or both sides of the viroid sequence(s) of a restriction fragment are precisely excised and are lacking in progeny viroids.
提出了一个将寡聚类病毒复制中间体加工成单体环状子代类病毒的模型。该模型确定了一种热力学上极其稳定的碱基配对构型，部分或完全二聚体以及更高的类病毒寡聚体可以呈现这种构型，并假设这种涉及所有类病毒共同结构特征（中央保守区和二级发夹I）的结构对于精确切割和连接至关重要。该模型解释了为什么含有两个或更多类病毒序列等同物串联重复的重组质粒接种到易受类病毒感染的植物中时具有高度传染性，为什么某些含有部分重复类病毒特异性插入片段的质粒传染性较低，以及为什么含有单体插入片段的质粒无传染性或至多具有微弱的传染性。该模型还解释了以下事实：限制片段的类病毒序列一侧或两侧的载体衍生序列被精确切除，并且在子代类病毒中不存在。
