Shirako Y, Wilson T M
Center for Agricultural Molecular Biology, Cook College, Rutgers University, New Brunswick, New Jersey 08903.
Virology. 1993 Jul;195(1):16-32. doi: 10.1006/viro.1993.1342.
The complete nucleotide sequences of RNAs 1 and 2 of soil-borne wheat mosaic virus (SBWMV), type member of the furovirus group, were determined. RNA 1 is 7099 nucleotides (nt) and encodes a 150-kDa protein from the 5' end region, the UGA termination codon of which can be partially read through to produce a 209-kDa protein, and a 37-kDa protein in the 3' end region. The C-terminal region of the 150-kDa protein contains an NTP-binding helicase motif and the readthrough region, an RNA polymerase motif, indicating that these two overlapping proteins may form an RNA replication complex similar to those of tobamo- and tobraviruses. The 37-kDa protein has sequence similarity with the cell-to-cell transport protein of dianthoviruses. RNA 2 is 3593 nt and, from the 5' end region, encodes the 19-kDa capsid protein, whose UGA termination codon can be partially suppressed to produce an 84-kDa readthrough protein and, at the 3' proximity, a 19-kDa protein which is rich in cysteine residues. The 28K (kilodaltons, as estimated by SDS-PAGE) protein, previously considered as another capsid readthrough product, is apparently initiated at an in-frame non-AUG codon upstream from the capsid protein gene. In both RNAs 1 and 2, the 5' terminus is capped, and the 3' untranslated region possibly forms internal consecutive pseudoknots as found in tobamovirus RNA as well as a terminal tRNA-like structure similar to tymovirus RNA. An amino acid sequence comparison of RNA replicase genes indicates that, phylogenetically, SBWMV belongs to a cluster formed by tobamo-, tobra-, and hordeiviruses. Differences in the 3' end structure and in the cell-to-cell movement protein, and the distant phylogeny of the RNA replicase genes of SBWMV and beet necrotic yellow vein virus, suggest that the furoviruses should be divided into at least two groups.
测定了土传小麦花叶病毒（SBWMV）RNA 1和RNA 2的完整核苷酸序列，SBWMV是真菌病毒属的典型成员。RNA 1有7099个核苷酸（nt），从5'端区域编码一个150 kDa的蛋白质，其UGA终止密码子可被部分通读以产生一个209 kDa的蛋白质，并在3'端区域编码一个37 kDa的蛋白质。150 kDa蛋白质的C端区域包含一个NTP结合解旋酶基序和通读区域，一个RNA聚合酶基序，表明这两个重叠蛋白可能形成类似于烟草花叶病毒和烟草脆裂病毒的RNA复制复合体。37 kDa蛋白质与石竹病毒的细胞间运输蛋白具有序列相似性。RNA 2有3593 nt，从5'端区域编码19 kDa的衣壳蛋白，其UGA终止密码子可被部分抑制以产生一个84 kDa的通读蛋白，并在3'端附近编码一个富含半胱氨酸残基的19 kDa蛋白质。先前被认为是另一种衣壳通读产物的28K（千道尔顿，通过SDS-PAGE估计）蛋白质显然起始于衣壳蛋白基因上游的一个框内非AUG密码子。在RNA 1和RNA 2中，5'端均被加帽，3'非翻译区可能形成类似于烟草花叶病毒RNA中发现的内部连续假结以及类似于芜菁黄花叶病毒RNA的末端tRNA样结构。RNA复制酶基因的氨基酸序列比较表明，从系统发育角度看，SBWMV属于由烟草花叶病毒、烟草脆裂病毒和大麦病毒形成的一个簇。SBWMV 3'端结构和细胞间运动蛋白的差异，以及SBWMV和甜菜坏死黄脉病毒RNA复制酶基因的远缘系统发育，表明真菌病毒应至少分为两组。
