Comparison of the reovirus serotype 1, 2, and 3 S3 genome segments encoding the nonstructural protein sigma NS.
Comparison of the reovirus serotype 1, 2, and 3 S3 genome segments encoding the nonstructural protein sigma NS.
复制标题
编码非结构蛋白 sigma NS 的呼肠孤病毒血清型 1、2 和 3 S3 基因组片段的比较。
DOI：
10.1016/0042-6822(87)90125-5
复制
发表时间：
1987
期刊：
影响因子：
3.7
通讯作者：
Joklik,WK
中科院分区：
文献类型：
--
作者：
Wiener,JR;Joklik,WK
提供了呼肠孤病毒血清型1和2原型毒株的S3基因组区段的序列，并将这些序列与血清型3 S3基因组区段的序列进行比较。S3基因组片段编码非结构蛋白σNS，其对ssRNA具有亲和力，并且似乎在呼肠孤病毒形态发生中起作用。三个S3基因组片段密切相关：都是1198个核苷酸长，并具有一个长的开放阅读框366个密码子长。它们表现出血清型1：3的相关模式：血清型1和3的S3基因组片段之间只有13%的错配，但血清型1和2以及血清型3和2之间分别有27%和26%的错配。三种σNS蛋白的氨基酸错配要低得多（分别为2.7%、13.9%和13.7%），因为大多数核苷酸错配位于第三碱基密码子位置。这三种σNS蛋白具有保守的二级结构，富含α-螺旋含量;事实上，这些非结构蛋白的预测α-螺旋含量（约50%）远高于其他三种σ大小类蛋白（约20%），所有这些蛋白都是结构蛋白。我们还对通过亚硝酸处理产生的血清型3的ts突变体的S3基因组片段进行了测序，发现了一个单核苷酸变化，该变化指定了一个氨基酸变化，该变化将5个残基长的β折叠倾向构型引入σNS C-末端一半的长（80个氨基酸）高度保守的α-螺旋中。这种变化可以解释这种突变体的性格。最后，三个σNS蛋白仅在约10%的位置处发生分歧，而三个σ1蛋白在约70%的位置处发生分歧。后者的快速进化分化可能是几个因素的结果，包括：（i）σ1而不是σNS受到免疫选择压力的事实;（ii）σ1的功能（抗原性和细胞附着）可能存在于两个相对于彼此在空间上不受限制的相当小的结构域;和（iii）σNS的功能，即RNA结合和蛋白质结合（在形态发生过程中），需要高度特异性的整体蛋白质构型，这可能允许很少的变化。
The sequences of the S3 genome segments of reovirus serotype 1 and 2 prototype strains are presented and these sequences are compared with the sequence of the serotype 3 S3 genome segment. The S3 genome segment encodes the nonstructural protein σNS which possesses affinity for ssRNA and appears to function in reovirus morphogenesis. The three S3 genome segments are closely related: all are 1198 nucleotides long and possess a single long open reading frame 366 codons long. They exhibit a serotype 1:3 relatedness pattern: there are only 13% mismatches between the S3 genome segments of serotypes 1 and 3, but 27 and 26% mismatches, respectively, between those of serotype 1 and 2 and serotype 3 and 2. The amino acid mismatches for the three σNS proteins are much lower (2.7, 13.9, and 13.7%, respectively), because the majority of nucleotide mismatches are in third base codon positions. The three σNS proteins possess a conserved secondary structure that is rich in α-helix content; in fact, the predicted α-helix content of these nonstructural proteins (about 50%) is much higher than that of the three other σ size class proteins (about 20%), all of which are structural proteins. We also sequenced the S3 genome segment of a ts mutant of serotype 3 generated by treatment with nitrous acid and found a single nucleotide change that specifies an amino acid change that introduces a five-residue-long β-sheet prone configuration into a long (80 amino acids) highly conserved α-helix in the C-terminal half of σNS. This change could account for this mutant's is character. Finally, the three σNS proteins have diverged in only about 10% of positions, whereas the three σ1 proteins have diverged in about 70%. The rapid evolutionary divergence of the latter may be a result of several factors, including (i) the fact that σ1, but not σNS, is under immunologic selective pressure; (ii) the fact that the functions of σ1 (antigenicity and cell attachment) probably reside in two rather small domains that are not restricted spatially with respect to each other; and (iii) the fact that the functions of σNS, namely RNA binding and protein binding (during morphogenesis), require a highly specific overall protein configuration that may permit little variation.