Evolution of reovirus genes: a comparison of serotype 1, 2, and 3 M2 genome segments, which encode the major structural capsid protein mu 1C.
Evolution of reovirus genes: a comparison of serotype 1, 2, and 3 M2 genome segments, which encode the major structural capsid protein mu 1C.
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DOI：
10.1016/0042-6822(88)90301-7
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发表时间：
1988-04
期刊：
影响因子：
3.7
通讯作者：
J. Wiener;W. Joklik
中科院分区：
文献类型：
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作者：
J. Wiener;W. Joklik
给出了呼肠孤病毒血清型1和2的M2基因组片段序列，并与血清型3的同源基因组片段进行了比较。基因组片段M2编码蛋白质μ1，其裂解产物μ1C是呼肠孤病毒颗粒的主要成分。3个M2基因组片段表现出血清型1:3的相关性模式：血清型1和3、1和2、2和3基因组片段对分别表现出15,23和23%的核苷酸不匹配。这些错配绝大多数（约87%）发生在不会引起氨基酸变化的第三碱基密码子位置；结果表明，这3种μ1蛋白的相关性非常高（约为97%）。μl蛋白为酸性蛋白，半胱氨酸、组氨酸和蛋氨酸含量低，脯氨酸含量丰富；预测α-螺旋含量较低，为27%。蛋白质μ1被切割成μ1C的位点预计位于分子高度保守部分的42和43残基之间。3个M2基因组片段的相关性显著高于3个S3基因组片段，远高于3个S1基因组片段。我们分析了这三个基因组片段的进化分化模式。在所有三个基因组片段中，第三个碱基密码子位置的错配积累率大致相同，但第一碱基密码子位置的错配积累率，特别是第二碱基密码子位置的错配积累率却大不相同。对于S1基因组片段，所有三个密码子位置的错配积累率差异不大，这表明功能保留与非常广泛的结构灵活性是相容的。相比之下，编码非结构蛋白σNS的S3基因组片段的第一和第二碱基密码子位置的错配积累率要低得多，而M2基因组片段的错配积累率更低，这表明蛋白质μ1C存在非常严格的结构约束，这可能是一个衣壳体成分的蛋白质所期望的。
The sequences of the M2 genome segments of reovirus serotypes 1 and 2 are presented and compared with that of the cognate genome segment of reovirus serotype 3. Genome segment M2 encodes protein μ1, a cleavage product of which, μ1C, is the major constituent of reovirus particles. The three M2 genome segments exhibit a serotype 1:3 relatedness pattern: the serotype 1 and 3, 1 and 2, and 2 and 3 genome segment pairs exhibit 15, 23, and 23% nucleotide mismatches, respectively. The vast majority of these mismatches (about 87%) occur in third base codon positions that do not cause amino acid changes; as a result the three μ1 proteins are very highly related (about 97%). The μl proteins are acidic proteins, low in cysteine, histidine, and methionine, and rich in proline; and they possess a rather low predicted α-helix content of 27%. The site where protein μ1 is cleaved to μ1C is predicted to be between residues 42 and 43 in a highly conserved portion of the molecule. The three M2 genome segments are related significantly more closely than the three S3 genome segments, and much more closely than the three S1 genome segments. We have analyzed the evolutionary divergence patterns of these three genome segments. The rate of mismatch accumulation in third base codon positions is roughly the same for all three genome segments, but the rates of mismatch accumulations in first, and particularly in second, base codon positions are quite different. For the S1 genome segments there is little difference between the rates of mismatch accumulations in all three codon positions, which indicates that retention of function is compatible with very extensive structural flexibility. By contrast, the rates of mismatch accumulations in first and second base codon positions are far less for the S3 genome segments, which encode the nonstructural protein σNS, and much lower still for the M2 genome segments, which suggests the existence of very stringent structural constraints for protein μ1C, which might be expected of a protein that is a capsomer component.