Functions of the 126-and 183-kDa proteins of tobacco mosaic virus
Functions of the 126-and 183-kDa proteins of tobacco mosaic virus
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DOI：
10.1006/viro.2000.0313
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发表时间：
2000-05-25
期刊：
影响因子：
3.7
通讯作者：
Dawson, WO
中科院分区：
文献类型：
--
作者：
Lewandowski, DJ;Dawson, WO
烟草花叶病毒产生两种蛋白质，所述蛋白质含有类似于其它RNA病毒的复制酶相关蛋白的甲基转移酶（MT）和解旋酶（HEL）样结构域的结构域。更丰富的126-kDa蛋白质仅含有MT和MEL样结构域，而183-kDa通读蛋白质另外含有聚合酶结构域。我们研究了这些蛋白质的功能，通过构建一个二分系统，从单独的RNA表达126-和183-kDa的蛋白质。表达183 kDa蛋白质的突变体识别负链和正链RNA合成的启动子，转录亚基因组mRNA，加帽RNA，合成蛋白质，在植物内移动细胞到细胞，并复制缺陷RNA（dRNA）。126-kDa蛋白的主要功能是使复制速率增加约10倍。126-kDa蛋白似乎主要以顺式发挥作用，反式126-kDa蛋白的产生并不增强辅助病毒的复制。产生功能性126-kDa蛋白的dRNA被仅产生183-kDa蛋白的辅助病毒有效复制，但野生型病毒不能，这表明有效复制需要183-kDa蛋白与已经结合到靶dRNA的126-kDa蛋白形成异源二聚体。(C)北京大学出版社.
Tobacco mosaic virus produces two proteins that contain domains similar to the methyltransferase (MT) and helicase (HEL)-like domains of the replicase-associated proteins of other RNA viruses. The more abundant 126-kDa protein contains only the MT and MEL-like domains, whereas the 183-kDa readthrough protein additionally contains the polymerase domain. We examined the functions of these proteins by constructing a bipartite system to express the 126- and 183-kDa proteins from separate RNAs. Mutants expressing the 183-kDa protein recognized promoters for negative- and positive-stranded RNA synthesis, transcribed subgenomic mRNAs, capped RNAs, synthesized proteins, moved cell to cell within the plant, and replicated defective RNAs (dRNAs). The principal function of the 126-kDa protein was to increase the rate of replication approximately tenfold. The 126-kDa protein appeared to function primarily in cis, and production of the 126-kDa protein in trans did not enhance replication of the helper virus. dRNAs producing a functional 126-kDa protein were replicated efficiently by helper viruses that produced only the 183-kDa protein but not by wild-type virus, suggesting that efficient replication required the 183-kDa protein to form a heterodimer with the 126-kDa protein already bound to the target dRNA. (C) 2000 Academic Press.