Receptor recognition mechanisms of coronaviruses

描述(申请人提供)：病毒对受体的识别是病毒感染的第一步，也是必不可少的一步。它是病毒宿主范围和跨物种感染的重要决定因素，也是人类干预的主要目标。冠状病毒识别多种受体，感染许多宿主，对人类和其他动物的健康构成重大威胁。NL63冠状病毒(NL63-CoV)是一种流行的人类呼吸道病毒，是目前已知的唯一一种以血管紧张素转换酶2(ACE2)为受体的I型冠状病毒，而其他I型冠状病毒则以氨基肽酶-N(APN)为受体。奇怪的是，ACE2也被第二组SARS冠状病毒(SARS-CoV)使用，SARS-CoV是致命的人类严重急性呼吸综合征(SARS)的制剂。NL63-CoV和SARS-CoV刺突蛋白上定义的受体结合域与ACE2具有高亲和力。本研究探讨冠状病毒的受体识别机制和跨物种感染。我们的初步研究确定了NL63冠状病毒RBD与人ACE2的络合物和SARS冠状病毒RBD与人ACE2的络合物的晶体结构。NL63-CoV和SARS-CoV rbd在直接与ACE2接触的核心或受体结合基序(RBM)上没有结构上的同源性，但识别ACE2上的相同“病毒结合热点”。在I组冠状病毒中，RBD核心是保守的，但RBM是可变的，这解释了这些病毒如何识别不同的受体。我们还测定了SARS冠状病毒不同毒株与人和果子狸ACE2蛋白的RBD的晶体结构，揭示了SARS冠状病毒在两种宿主之间传播的机制。这个项目有三个具体目标。目的1研究I组NL63冠状病毒的受体识别机制。它研究了人ACE2上的病毒结合热点在NL63-CoV结合中的特定功能，并检测了NL63-CoV刺突蛋白与非人类宿主ACE2蛋白之间的相互作用。目的研究其他I组冠状病毒的受体识别机制。它研究了其他I组冠状病毒S蛋白的RBM的特定功能，并研究了修饰RBM是否改变了S蛋白的受体特异性。目的研究第二组SARS冠状病毒的受体识别机制。它调查了为什么选择过去SARS-CoV毒株的RBM区域的突变，这些突变是否以及如何影响受体结合，以及这些突变的什么组合可能出现在未来的SARS-CoV潜在毒株中。这一建议的研究方法包括对病毒-受体界面的结晶学分析，对病毒-受体相互作用重要的结构元件的鉴定，以及使用结晶学、生化、分子和病毒学工具对这些元件进行表征。总体而言，这些研究将为了解病毒进化、病毒-受体相互作用、病毒宿主范围和跨物种感染提供分子和结构基础。它们还将指导开发针对冠状病毒感染的新型抗病毒策略。 公共卫生相关性：这项研究调查了冠状病毒如何识别它们的受体，以及它们如何与来自不同宿主的受体相互作用。它探索了管理病毒进化、病毒-受体相互作用、病毒宿主范围和跨物种感染的新原理，并可能导致预防和治疗人类和其他动物冠状病毒感染的新方法。

DESCRIPTION (provided by applicant): Receptor recognition by viruses is the first and essential step of viral infections. It is an important determinant of viral host ranges and cross-species infections, and a primary target for human intervention. Coronaviruses recognize a variety of receptors, infect many hosts, and are significant health threats to humans and other animals. NL63 coronavirus (NL63-CoV), a prevalent human respiratory virus, is the only group-I coronavirus known to use angiotensin-converting enzyme 2 (ACE2) as its receptor, whereas other group-I coronaviruses use aminopeptidase-N (APN). Curiously, ACE2 is also used by group-II SARS coronavirus (SARS-CoV), the agent for the fatal human severe acute respiratory syndrome (SARS). Defined receptor-binding domains (RBDs) on the spike proteins of NL63-CoV and SARS-CoV bind ACE2 with high affinity. This research investigates the receptor recognition mechanisms and cross-species infections of coronaviruses. Our preliminary studies have determined the crystal structures of NL63-CoV RBD complexed with human ACE2 and of SARS-CoV RBD complexed with human ACE2. NL63-CoV and SARS-CoV RBDs have no structural homology in cores or receptor-binding motifs (RBMs) that directly contact ACE2, but recognize the same "virus-binding hotspot" on ACE2. Among group-I coronaviruses, RBD cores are conserved, but RBMs are variable, explaining how these viruses recognize different receptors. We have also determined crystal structures of the RBDs from various SARS-CoV strains complexed with ACE2 proteins from humans and palm civets, revealing mechanisms whereby SARS-CoV transmitted between the two hosts. There are three specific aims in this project. Aim 1 focuses on the receptor recognition mechanisms of group-I NL63-CoV. It investigates specific functions of the virus-binding hotspot on human ACE2 in NL63-CoV binding, and examines interactions between the NL63-CoV spike protein and ACE2 proteins from non-human hosts. Aim 2 focuses on the receptor recognition mechanisms of other group-I coronaviruses. It investigates specific functions of the RBMs of other group-I coronavirus spike proteins, and studies whether modifying the RBMs changes the receptor specificities of the spike proteins. Aim 3 focuses on the receptor recognition mechanisms of group-II SARS-CoV. It investigates why mutations in the RBM region of past SARS-CoV strains were selected, whether and how these mutations affect receptor binding, and what combinations of these mutations may appear in potential future SARS-CoV strains. The research approaches of this proposal include crystallographic analysis of the virus-receptor interfaces, identification of structural elements important for virus-receptor interactions, and characterization of these elements using crystallographic, biochemical, molecular, and virological tools. Overall, these studies will provide the molecular and structural basis for understanding viral evolution, virus-receptor interactions, viral host ranges and cross-species infections. They will also guide the development of novel antiviral strategies against coronavirus infections. PUBLIC HEALTH RELEVANCE: This research investigates how coronaviruses recognize their receptors and how they interact with receptors from different hosts. It explores novel principles governing viral evolution, virus-receptor interactions, viral host ranges and cross-species infections, and may lead to new approaches in the prevention and treatment of coronavirus infections in humans and other animals.