Zebrafish ribonucleases are bactericidal: Implications for the origin of the vertebrate RNase a superfamily
Zebrafish ribonucleases are bactericidal: Implications for the origin of the vertebrate RNase a superfamily
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DOI：
10.1093/molbev/msm047
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发表时间：
2007-05-01
影响因子：
10.7
通讯作者：
Zhang, Jianzhi
中科院分区：
文献类型：
--
作者：
Cho, Soochin;Zhang, Jianzhi
了解核糖核酸酶（RNase）A超家族的进化起源是非常有趣的，因为该超家族是迄今为止已知的唯一脊椎动物特异性酶家族。尽管哺乳动物的核糖核酸酶具有多种多样的生物化学和生理功能，但该超家族在其诞生时的原始功能是神秘的。这样的信息可以通过研究脊椎动物生殖的基础谱系来获得，并且对于辨别这个超家族是如何以及为什么起源是必要的。在这里，我们克隆和表征3核糖核酸酶基因从斑马鱼，最基本的脊椎动物检查核糖核酸酶。我们报告1）所有3种斑马鱼RNA酶都具有核糖核酸水解活性，其中一种RNA酶的活性与牛RNA酶A（超家族的原型）相当; 2）2种斑马鱼RNA酶在成体肝脏和肠道中具有显著表达，而第3种RNA酶在成体眼睛和心脏中表达; 3）所有3种RNA酶都具有体外抗菌活性。这些结果，以及在多个远亲哺乳动物RNA酶中存在的抗菌和/或抗病毒活性，强烈表明该超家族在脊椎动物进化中开始作为宿主防御机制。
Understanding the evolutionary origin of the ribonuclease (RNase) A superfamily is of great interest because the superfamily is the sole vertebrate-specific enzyme family known to date. Although mammalian RNases have a diverse array of biochemical and physiological functions, the original function of the superfamily at its birth is enigmatic. Such information may be obtained by studying basal lineages of the vertebrate phylogeny and is necessary for discerning how and why this superfamily originated. Here, we clone and characterize 3 RNase genes from the zebrafish, the most basal vertebrate examined for RNases. We report 1) that all the 3 zebrafish RNases are ribonucleolytically active, with one of them having an RNase activity comparable to that of bovine RNase A, the prototype of the superfamily; 2) that 2 zebrafish RNases have prominent expressions in adult liver and gut, whereas the 3rd is expressed in adult eye and heart; and 3) that all 3 RNases have antibacterial activities in vitro. These results, together with the presence of antibacterial and/or antiviral activities in multiple distantly related mammalian RNases, strongly suggest that the superfamily started as a host-defense mechanism in vertebrate evolution.