Koonin E V, Choi G H, Nuss D L, Shapira R, Carrington J C
Department of Biology, Texas A&M University, College Station 77843.
Proc Natl Acad Sci U S A. 1991 Dec 1;88(23):10647-51. doi: 10.1073/pnas.88.23.10647.
Computer-assisted analysis of the putative polypeptide products encoded by the two open reading frames present in a large virus-like double-stranded RNA, L-dsRNA, associated with hypovirulence of the chestnut blight fungus, Cryphonectria parasitica, revealed five distinct domains with significant sequence similarity to previously described conserved domains within plant potyvirus-encoded polyproteins. These included the putative RNA-dependent RNA polymerase, RNA helicase, two papain-like cysteine proteases related to the potyvirus helper-component protease, and a cysteine-rich domain of unknown function similar to the N-terminal portion of the potyvirus helper-component protein. Phylogenetic trees derived from the alignment of the polymerase domains of L-dsRNA, a subset of positive-stranded RNA viruses, and double-stranded RNA viruses, using three independent algorithms, suggested that the hypovirulence-associated dsRNA and potyvirus genomes share a common ancestry. However, comparison of the organization of the conserved domains within the encoded polyproteins of the respective viruses indicated that the proposed subsequent evolution involved extensive genome rearrangement.
对一种与栗疫病菌（Cryphonectria parasitica）低毒力相关的大型病毒样双链RNA（L-dsRNA）中存在的两个开放阅读框编码的假定多肽产物进行计算机辅助分析，发现了五个不同的结构域，它们与植物马铃薯Y病毒编码的多聚蛋白中先前描述的保守结构域具有显著的序列相似性。这些结构域包括假定的RNA依赖性RNA聚合酶、RNA解旋酶、两种与马铃薯Y病毒辅助成分蛋白酶相关的类木瓜蛋白酶半胱氨酸蛋白酶，以及一个功能未知的富含半胱氨酸的结构域，类似于马铃薯Y病毒辅助成分蛋白的N端部分。使用三种独立算法，由L-dsRNA、正链RNA病毒的一个子集和双链RNA病毒的聚合酶结构域比对得出的系统发育树表明，与低毒力相关的双链RNA和马铃薯Y病毒基因组有共同的祖先。然而，对各病毒编码的多聚蛋白中保守结构域的组织进行比较表明，所提出的后续进化涉及广泛的基因组重排。
