Rohll J B, Holness C L, Lomonossoff G P, Maule A J
Department of Virus Research, John Innes Institute, Norwich, United Kingdom.
Virology. 1993 Apr;193(2):672-9. doi: 10.1006/viro.1993.1175.
The location of nucleotide sequences important in determining the extent of cowpea mosaic virus M-RNA accumulation in cowpea protoplasts has been analyzed by deletion mutagenesis of full-length cDNA clones from which infectious transcripts can be produced in vitro. The results suggest that cis-acting sequences which direct replication of M-RNA by B-RNA-encoded products are located within the 5'-terminal 524 nucleotides and the 3'-terminal 151 nucleotides. RNA secondary structure predictions for the 3'-terminal 151 nucleotides of both genomic RNAs (Eggen et al. (1989) Virology 173, 456-464) indicate that the terminal nucleotides form a stable secondary structure composed of a Y-shaped stem-loop and a simple A-U-rich stem-loop. The latter structure has been implicated in B-RNA replication. We have examined the role of the Y-shaped structure in M-RNA accumulation by site-directed mutagenesis of putative base-pairing combinations in the two minor stems. The results suggest that efficient replication is dependent on the formation of both of these minor stem structures.
通过对全长cDNA克隆进行缺失诱变分析了在决定豇豆原生质体中豇豆花叶病毒M-RNA积累程度方面重要的核苷酸序列的位置，从这些全长cDNA克隆可在体外产生感染性转录本。结果表明，由B-RNA编码产物指导M-RNA复制的顺式作用序列位于5'-末端524个核苷酸和3'-末端151个核苷酸内。对两种基因组RNA的3'-末端151个核苷酸的RNA二级结构预测（Eggen等人，（1989年）《病毒学》173卷，456 - 464页）表明，末端核苷酸形成由Y形茎环和简单富含A-U的茎环组成的稳定二级结构。后一种结构与B-RNA复制有关。我们通过对两个小茎中假定碱基配对组合进行定点诱变研究了Y形结构在M-RNA积累中的作用作用。结果表明，高效复制依赖于这两个小茎结构的形成。
