Huan B F, Shen Y Q, Bruenn J A
Department of Biological Sciences, State University of New York, Buffalo 14260.
Proc Natl Acad Sci U S A. 1991 Feb 15;88(4):1271-5. doi: 10.1073/pnas.88.4.1271.
The Saccharomyces cerevisiae viruses are noninfectious double-stranded RNA viruses whose segments are separately encapsidated. A large viral double-stranded RNA (L1; 4580 base pairs) encodes all required viral functions. M1, a double-stranded RNA of 1.9 kilobases, encodes an extracellular toxin (killer toxin) and cellular immunity to that toxin. Some strains contain smaller, S, double-stranded RNAs, derived from M1 by internal deletion. Particles containing these defective interfering RNAs can displace M1 particles by faster replication and thus convert the host strain to a nonkiller phenotype. In this work, we report the development of an assay in which the expression of S plus-strand from an inducible plasmid causes the loss of M1 particles. This assay provides a convenient method for identifying in vivo cis-acting sequences important in viral replication and packaging. We have mapped the sequence involved in interference to a region of 132 base pairs that includes two sequences similar to the viral binding site sequence previously identified in L1 by in vitro experiments.
酿酒酵母病毒是无感染性的双链RNA病毒，其片段分别被包裹。一个大的病毒双链RNA（L1；4580个碱基对）编码所有必需的病毒功能。M1是一个1.9千碱基的双链RNA，编码一种细胞外毒素（杀伤毒素）以及对该毒素的细胞免疫。一些菌株含有较小的S双链RNA，它是通过M1内部缺失产生的。含有这些缺陷干扰RNA的颗粒可以通过更快的复制取代M1颗粒，从而将宿主菌株转变为非杀伤表型。在这项工作中，我们报告了一种检测方法的开发，其中从可诱导质粒表达的S正链会导致M1颗粒的丢失。该检测方法为鉴定病毒复制和包装中重要的体内顺式作用序列提供了一种便捷方法。我们已将参与干扰的序列定位到一个132个碱基对的区域，该区域包含两个与先前通过体外实验在L1中鉴定的病毒结合位点序列相似的序列。
