The ribonuclease A superfamily of mammals and birds: identifying new members and tracing evolutionary histories
The ribonuclease A superfamily of mammals and birds: identifying new members and tracing evolutionary histories
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DOI：
10.1016/j.ygeno.2004.10.008
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发表时间：
2005-02-01
期刊：
影响因子：
4.4
通讯作者：
Zhang, JZ
中科院分区：
文献类型：
--
作者：
Cho, S;Beintema, JJ;Zhang, JZ
RNase A超家族在生物化学、结构和进化研究中具有重要意义，被认为是唯一的脊椎动物特异性酶家族。为了了解该超家族的起源和多样化，我们在这里确定了人类，小鼠，大鼠和鸡的测序基因组中的整个剧目。我们报告了小鼠10号染色体上一个以前未被注意的基因簇和一些新基因，包括哺乳动物RNA酶11-13，它们是最近发现的RNA酶9和10的近亲。基因表达数据暗示RNascs 9-13的雄性生殖功能，尽管它们的序列表明缺乏核糖核酸溶解活性。与哺乳动物中存在13-20个功能基因相比，鸡只有3个RNase基因，与其他非哺乳动物RNase一样，它们在进化上接近哺乳动物RNase 5。这个和其他证据表明，RNase A超家族起源于RNase 5样基因，并在哺乳动物中扩展。再加上该超家族的多个谱系，包括RNA酶2、3、5和7，具有抗病原体活性的事实，我们认为该超家族在脊椎动物中是作为宿主防御机制开始的。与这一假设一致，超家族的所有成员都表现出高速率的氨基酸取代，这在免疫基因中是常见的。(C)2004爱思唯尔公司All rights reserved.
The RNase A superfamily has been important in biochemical, structural, and evolutionary studies and is believed to be the sole vertebratespecific enzyme family. To understand the origin and diversification of the superfamily, we here determine its entire repertoire in the sequenced genomes of human, mouse, rat, and chicken. We report a previously unnoticed gene cluster in mouse chromosome 10 and a number of new genes, including mammalian RNases 11-13, which are close relatives of the recently identified RNases 9 and 10. Gene expression data imply male-reproductive functions for RNascs 9-13, although their sequences suggest the lack of ribonucleolytic activities. In contrast to the presence of 13-20 functional genes in mammals, chicken has only 3 RNase genes, which are evolutionarily close to mammalian RNase 5, like other nonmammalian RNases. This and other evidence suggests that the RNase A superfamily originated from an RNase 5-like gene and expanded in mammals. Together with the fact that multiple lineages of the superfamily, including RNases 2, 3, 5, and 7, have antipathogenic activities, we suggest that the superfamily started off as a host-defense mechanism in vertebrates. Consistent with this hypothesis, all members of the superfamily exhibit high rates of amino acid substitution as is commonly observed in immunity genes. (C) 2004 Elsevier Inc. All rights reserved.