RNases for understanding the origin of new gene function

我的实验室的长期目标是了解具有新功能的新基因是如何产生和 这些分子创新如何有助于有机体的生存、适应和进化。 尽管众所周知，《飘》的复制在小说《飘》的演变中起着重要作用 复制的功能、进化力量和功能变化的分子机制 人们对基因仍然知之甚少。这里使用的是哺乳动物的核糖核酸酶(RNase)基因超家族 作为解决上述问题的典范系统，因为(1)超家族最近包括了许多 具有不同功能的复制基因，(2)这些功能在体外可以相对容易地检测，用 分析定点突变产生的突变蛋白的可行性，(3) 超级家族参与免疫和癌症，并与人类健康有关，以及(4)大量 关于超家族的生化、结构和功能信息是可用的。委员会的八名成员 超家族在人类中已知，它们是胰腺RNase(或RNase1)，嗜酸性粒细胞来源 神经毒素(EDN或RNase2)、嗜酸性粒细胞阳离子蛋白(ECP或RNase3)、RNase4、血管生成素(或 RNase5)、RNaseK6(或RNase6)、RNase7和RNase8。作为酶，它们都可以裂解 RNA中的磷脂二酯键。但它们也进化了其他功能，并参与了各种 生理过程包括食物RNA的消化、血管生成和宿主防御。我们的特定 目的是(1)通过功能表征来检验关于新基因功能起源的两种相互竞争的理论 在高等灵长类动物复制的EDN和ECP基因的重建共同祖先GOE中， 分别具有抗病毒和抗细菌活性；(2)鉴定氨基酸替代 负责ECP的抗菌功能；(3)确定导致强效的氨基酸取代 EDN中的核糖核酸酶活性和抗病毒活性；(3)调查最近出现的一种杀菌剂 人类RNase7基因的等位基因形式及其在人类健康和进化中的潜在作用；(5) 研究类人猿RNase8中二硫键桥联的进化及其功能后果 由二硫键的变化引起；以及(6)研究灵长类血管生成素快速进化的原因 并鉴定血管生成素中血管生成活性所必需的关键氨基酸残基。

The long-term objective of my laboratory is to understand how new genes with novel functions originate and how these molecular innovations contribute to the survival, adaptation, and evolution of organisms. Although it is well known that gone duplication plays an important role in the evolution of novel gone functions, the evolutionary forces and molecular mechanisms underlying functional changes of duplicated genes remain poorly understood. Here the ribonuclease (RNase) A gene superfamily of mammals is used as a model system to address the above questions, because (1) the superfamily includes many recently duplicated genes with distinct functions, (2) these functions can be assayed relatively easily in vitro, with the feasibility of analyzing mutant proteins generated by site-directed mutagenesis, (3) members of the superfamily are involved in immunity and cancer and are related to human health, and (4) substantial biochemical, structural, and functional information is available on the superfamily. Eight members of the superfamily are known in humans, and they are pancreatic RNase (or RNase 1), eosinophil-derived neurotoxin (EDN or RNase 2), eosinophil cationic protein (ECP or RNase 3), RNase 4, angiogenin (or RNase 5), RNase k6 (or RNase 6), RNase 7, and RNase 8. As enzymes, all of them can cleave phospodiester bonds in RNA. But they have also evolved other functions and are involved in various physiological processes including digestion of dietary RNAs, angiogenesis, and host defenses. Our specific aims are (1) to test two competing theories on the origin of new gene function by functional characterization of the reconstructed common ancestral gone of the duplicated EDN and ECP genes of higher primates, which have antiviral and antibacterial activities, respectively; (2) to identify amino acid substitutions responsible for the antibacterial function of ECP; (3) to identify amino acid substitutions that led to the potent ribonuclease activity and antiviral activity in EDN; (3) to investigate the recent emergence of an bactericidal alleleic form of the RNase 7 gene in humans and to test its potential role in human health and evolution; (5) to study the evolution of disulfide-bridging in RNase 8 among hominoids and the functional consequences cause by changes in disulfide bonds; and (6) to study the cause of the rapid evolution of primate angiogenin and to identify key amino acid residues necessary for the angiogentic activity in angiogenin.