Carpenter C D, Simon A E
Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst 01003, USA.
Virology. 1996 Sep 1;223(1):165-73. doi: 10.1006/viro.1996.0465.
Recombinant RNAs generated in plants 3 weeks postinoculation with turnip crinkle virus (TCV) genomic RNA and an associated satellite RNA, sat-RNA D, have a majority of TCV crossover sites in a 24-nucleotide repeat (motif IIIA/IIIB) that forms part of a stable hairpin (Carpenter et al., 1995, J. Mol.Biol. 245, 608-622). To determine if parameters other than nucleotide sequence in the crossover region affect junction site selection, recombinants were assayed at various times postinoculation of plants and protoplasts. Populations of recombinants became progressively shorter in plants and larger in protoplasts. Levels of inoculated transcript and age of the plant were not substantial factors in the shifts in crossover site locations. The two most commonly cloned recombinant species were not amplified to detectable levels in protoplasts, suggesting that these molecules are not viable templates for replication. These results suggest that recombination between sat-RNA D and TCV is a very frequent event, and populations of recombinants are likely generated de novo in each infected cell and represent the original recombinant molecules rather than progeny of such molecules. Therefore, factors other than simple selection for recombinants that are more fit to replicate are probably responsible for the differences in junction sites in populations of sat-RNA D/TCV recombinants.
在用芜菁皱缩病毒（TCV）基因组RNA和相关卫星RNA（sat-RNA D）接种植物3周后产生的重组RNA，其大部分TCV交叉位点位于一个24核苷酸重复序列（基序IIIA/IIIB）中，该重复序列构成一个稳定发夹结构的一部分（Carpenter等人，1995年，《分子生物学杂志》245卷，608 - 622页）。为了确定交叉区域中除核苷酸序列以外的参数是否影响连接位点的选择，在接种植物和原生质体后的不同时间对重组体进行了检测。植物中的重组体群体逐渐变短，而原生质体中的则逐渐变大。接种转录本的水平和植物的年龄并不是交叉位点位置变化的重要因素。两种最常克隆的重组体在原生质体中未扩增到可检测水平，这表明这些分子不是可行的复制模板。这些结果表明，sat-RNA D和TCV之间的重组是一个非常频繁的事件，重组体群体可能在每个受感染细胞中从头产生，代表原始的重组分子而非此类分子的后代。因此，除了简单选择更适合复制的重组体外，其他因素可能导致了sat-RNA D/TCV重组体群体中连接位点的差异。
