RNases for understanding the origin of new gene function

超出提供的空间。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的，以及这些分子创新如何为生物体的生存、适应和进化做出贡献。虽然众所周知，Gone复制在新的Gone功能的进化中起着重要的作用，但复制基因的功能变化背后的进化力量和分子机制仍然知之甚少。本文以哺乳动物的核糖核酸酶(RNase)基因超家族作为模型系统来解决上述问题，因为(1)超家族包括许多最近复制的具有不同功能的基因，(2)这些功能可以相对容易地在体外进行检测，并有可能分析通过定点突变产生的突变蛋白，(3)超家族成员参与免疫和癌症并与人类健康有关，以及(4)关于超家族的大量生化、结构和功能信息。在人类中已知的超家族有8个成员，它们是胰腺RNase1、嗜酸性粒细胞源性神经毒素(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，它们都能裂解RNA中的磷脂二酯键。但它们还进化了其他功能，并参与了各种生理过程，包括消化食物RNA、血管生成和宿主防御。我们的具体目标是(1)通过对具有抗病毒和抗细菌活性的高等灵长类动物复制的EDN和ECP基因的重建共同祖先GOE的功能特征来测试关于新基因功能起源的两种相互竞争的理论；(2)确定与ECP的抗菌功能有关的氨基酸替换；(3)确定导致EDN中具有强大的核糖核酸酶活性和抗病毒活性的氨基酸替换；(3)调查最近在人类中出现的杀菌的RNase7基因的等位基因形式，并测试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以及二硫键变化所导致的功能后果；(6)研究灵长类血管生成素快速进化的原因，并确定血管生成素中血管生成活性所必需的关键氨基酸残基。表演网站========================================Section End===========================================

EXCEED THE SPACE PROVIDED. 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. PERFORMANCE SITE ========================================Section End===========================================