Rozanov M N, Koonin E V, Gorbalenya A E
Institute of Molecular Biology, Russian Academy of Sciences, Moscow.
J Gen Virol. 1992 Aug;73 ( Pt 8):2129-34. doi: 10.1099/0022-1317-73-8-2129.
Computer-assisted comparisons of the large proteins involved in the replication of viral RNA have revealed a novel domain located near the N termini of these proteins and conserved throughout the so-called 'Sindbis-like' supergroup of positive-strand RNA viruses. This domain encompasses four distinct conserved motifs, with motifs I, II and IV containing an invariant His residue, the AspXXArg signature and an invariant Tyr residue, respectively. Each of the two large groups of viruses within this supergroup, the 'altovirus' group (alphaviruses, tobamoviruses, tobraviruses, hordeiviruses, tricornaviruses, furoviruses, hepatitis E virus and probably rubiviruses), and the 'typovirus' group (tymoviruses, potexviruses, carlaviruses and apple chlorotic leaf spot virus), can be characterized by additional conserved sequence motifs. Based on the available results of biochemical studies and site-directed mutagenesis of the alphavirus proteins, it is hypothesized that this domain may be involved in methylation of the cap during viral RNA maturation. Unlike the other conserved domains, the RNA-dependent RNA polymerase and the RNA helicase, the motifs typical of the putative methyltransferase domain are universal within the Sindbis-like supergroup but are not found in the proteins of any other viruses, constituting a distinctive hallmark of this supergroup.
对参与病毒RNA复制的大蛋白进行计算机辅助比较，发现了一个位于这些蛋白N端附近的新结构域，该结构域在正链RNA病毒的所谓“辛德比斯样”超群中保守存在。这个结构域包含四个不同的保守基序，基序I、II和IV分别含有一个不变的组氨酸残基、AspXXArg特征序列和一个不变的酪氨酸残基。这个超群中的两大类病毒，即“阿尔托病毒”组（甲病毒、烟草花叶病毒、烟草脆裂病毒、大麦病毒、三叶草病毒、真菌传杆状病毒、戊型肝炎病毒以及可能的风疹病毒）和“典型病毒”组（芜菁黄花叶病毒、马铃薯X病毒、香石竹潜隐病毒和苹果褪绿叶斑病毒），可以通过其他保守序列基序来表征。基于甲病毒蛋白的生化研究和定点诱变的现有结果，推测该结构域可能参与病毒RNA成熟过程中帽结构的甲基化。与其他保守结构域（RNA依赖性RNA聚合酶和RNA解旋酶）不同，推定的甲基转移酶结构域的典型基序在辛德比斯样超群中是普遍存在的，但在任何其他病毒的蛋白中都未发现，构成了这个超群的一个独特标志。
