Strauss E G, Levinson R, Rice C M, Dalrymple J, Strauss J H
Division of Biology, California Institute of Technology, Pasadena 91125.
Virology. 1988 May;164(1):265-74. doi: 10.1016/0042-6822(88)90644-7.
We have sequenced the nsP3 and nsP4 region of two alphaviruses, Ross River virus and O'Nyong-nyong virus, in order to examine these viruses for the presence or absence of an opal termination codon present between nsP3 and nsP4 in many alphaviruses. We found that Ross River virus possesses an in-phase opal termination codon between nsP3 and nsP4, whereas in O'Nyong-nyong virus this termination codon is replaced by an arginine codon. Previous studies have shown that two other alphaviruses, Sindbis virus and Middelburg virus, possess an opal termination codon separating nsP3 and nsP4 [E.G. Strauss, C.M. Rice, and J.H. Strauss (1983), Proc. Natl. Acad. Sci. USA 80, 5271-5275], whereas Semliki Forest virus possesses an arginine codon in lieu of the opal codon [K. Takkinen (1986), Nucleic Acids Res. 14, 5667-5682]. Thus, of the five alphaviruses examined to date, three possess the opal codon and two do not. Production of nsP4 requires readthrough of the opal codon in those alphaviruses that possess this termination codon and the function of the termination codon may be to regulate the amount of nsP4 produced. It is an open question then as to whether alphaviruses with no termination codon use other mechanisms to regulate the activity of this gene. The nsP4s of these five alphaviruses are highly conserved, sharing 71-76% amino acid sequence similarity, and all five contain the Gly-Asp-Asp motif found in many RNA virus replicases. The nsP3s are somewhat less conserved, sharing 52-73% amino acid sequence similarity throughout most of the protein, but each possesses a nonconserved C-terminal domain of 134 to 246 amino acids of unknown function.
我们对两种甲病毒——罗斯河病毒和奥尼永永病毒的非结构蛋白3（nsP3）和非结构蛋白4（nsP4）区域进行了测序，以便检测这些病毒在nsP3和nsP4之间是否存在许多甲病毒中都有的乳白终止密码子。我们发现罗斯河病毒在nsP3和nsP4之间有一个同相位的乳白终止密码子，而在奥尼永永病毒中，这个终止密码子被一个精氨酸密码子取代。先前的研究表明，另外两种甲病毒——辛德毕斯病毒和米德尔堡病毒，在nsP3和nsP4之间也有一个乳白终止密码子[E.G.施特劳斯、C.M.赖斯和J.H.施特劳斯（1983年），《美国国家科学院院刊》80，5271 - 5275]，而塞姆利基森林病毒有一个精氨酸密码子替代了乳白密码子[K.塔基宁（1986年），《核酸研究》14，5667 - 5682]。因此，在迄今为止检测的五种甲病毒中，三种有乳白密码子，两种没有。在那些拥有这个终止密码子的甲病毒中，nsP4的产生需要通过乳白密码子的通读，并且这个终止密码子的功能可能是调节产生的nsP4的量。那么，对于没有终止密码子的甲病毒是否使用其他机制来调节这个基因的活性，这还是一个悬而未决的问题。这五种甲病毒 的nsP4高度保守，氨基酸序列相似性为71 - 76%，并且所有五种都含有许多RNA病毒复制酶中发现的甘氨酸 - 天冬氨酸 - 天冬氨酸基序。nsP3的保守性稍低，在蛋白质的大部分区域氨基酸序列相似性为52 - 73%，但每种都有一个134至246个氨基酸的功能未知的非保守C末端结构域。
