Understanding The Structural Basis of APOBEC Functions

说明(申请人提供)：APOBEC功能的结构基础APOBEC(载脂蛋白B mRNA编辑酶催化多肽)家族胞苷脱氨酶是脱氨基DNA/RNA胞苷残基的酶家族。APOBEC蛋白具有显著的细胞功能和抗病毒活性，这在一定程度上解释了近年来这一研究领域的强烈关注。APOBEC蛋白只在脊椎动物中发现，APOBEC3(Apo3)蛋白只在灵长类动物中发现。通过结合和脱氨基DNA/RNA，APOBEC酶实现了显著不同的细胞功能。例如，APOBEC1(Apo1)编辑与脂质代谢有关的蛋白质的mRNA；AID在抗体成熟的体细胞超突变中起关键作用；APOBEC2(APO2)可能对心肌发育起调节作用；Apo3蛋白，尤其是Apo3G，可以限制重要的病毒病原体，包括人类免疫缺陷病毒(HIV)和乙肝病毒(HBV)，以及逆转录元件的移动。因此，一种新的艾滋病毒治疗方法侧重于利用Apo3G和Apo3F的强大抗病毒活性。我们的长期目标是了解APOBEC细胞功能及其抗病毒活性的结构/功能关系。我们的具体目标是将我们先前在APOBEC蛋白质结构表征方面的成功扩展到APOBEC功能机制的结构基础的研究，包括它们的抗病毒活性，特别是Apo3G和Apo3F。这项研究将为了解APOBEC酶家族的分子细节提供有价值的信息，并为潜在的药物开发提供治疗艾滋病毒、免疫性疾病和其他与APOBEC功能或故障相关的疾病。公共卫生相关性：了解载脂蛋白BEC功能的结构基础载脂蛋白B信使核糖核酸编辑酶催化多肽(APOBEC)家族胞苷脱氨酶仅见于脊椎动物。APOBEC核酸脱氨酶通过使mRNA编码序列和单链DNA中的胞嘧啶脱氨基来修饰基因。它们的重要生物学作用包括脂类代谢、体液免疫反应以及对人体某些器官和生殖系统发育过程的潜在调节。此外，这些酶可以抑制逆转录病毒的复制，如人类免疫缺陷病毒(HIV)和乙肝病毒(乙肝)，以及反转录转座子。如果APOBEC蛋白的活性不受到严格控制，其重要的有益突变能力可能会损害基因组的稳定性。对APOBEC功能的分子机制的结构基础的了解仍然很少，具有科学意义和直接的健康相关性。我们建议以结构生物学为主，辅以生物物理学、分子生物学和功能生物化学，研究APOBEC脱氨酶家族的结构和功能，重点研究APOBEC3G和3F(Apo3G和3F)蛋白及其与细胞和病毒配体的相互作用。

DESCRIPTION (provided by applicant): The Structural Basis of APOBEC Functions The APOBEC (Apolioprotein B mRNA-editing Enzyme Catalytic polypeptide) family of cytidine deaminases is a family of enzymes that deaminate cytidine residues of DNA/RNA. APOBEC proteins possess significant cellular functions and anti-viral activity, which partially accounts for the intense attention to this the field of research in recent years. APOBEC proteins are found only in vertebrates and APOBEC3 (Apo3) proteins are found only in primates. By binding and deaminating DNA/RNA, APOBEC enzymes achieve remarkably diverse cellular functions. For example, APOBEC1 (Apo1) edits the mRNA of a protein involved in lipid metabolism; AID plays a key role in somatic hypermutation for antibody maturation; APOBEC2 (Apo2) may play a regulatory role for heart muscle development; and Apo3 proteins, especially Apo3G, can restrict important viral pathogens, including Human Immunodeficiency Virus (HIV) and Hepatitis B Virus (HBV), and retro-element mobility. As a result, a novel approach to HIV therapy focuses on utilizing the potent anti-viral activity of Apo3G and Apo3F. Our long-term goals are to understand the structural/functional relationship for APOBEC cellular function and their anti-viral activity. Our specific aims are to extend our prior success in the structural characterization of APOBEC proteins to the studies of the structural basis of APOBEC's functional mechanisms, including their antiviral activity, with particular focuses on Apo3G and Apo3F. The research will provide valuable information for understanding the molecular details of the APOBEC enzyme family and for the potential drug development to provide therapy for HIV, immune diseases and other diseases related to APOBEC function or malfunction. PUBLIC HEALTH RELEVANCE: Understanding The Structural Basis of APOBEC Functions The Apolioprotein B mRNA-editing enzyme catalytic polypeptide (APOBEC) family of cytidine deaminases are found exclusively in verterbrates. APOBEC nucleic acid deaminases modify genes by deaminating cytosines in mRNA coding sequences and in ssDNA. Their critical biological roles include lipid metabolism, humoral immune response, and potential regulations of developmental process of certain human organs and reproductive system. Additionally, these enzymes can inhibit the replication of retroviruses, such as the human immunodeficiency virus (HIV) and hepatitis B virus (HBV), and retrotransposons. The important beneficial mutational ability of APOBEC proteins can become detrimental to the stability of genome if their activity is not tightly regulated. The understanding of the structural basis of the molecular mechanisms of APOBEC function, which is still poorly understood, bears scientific significance and direct health relevance. We propose to study the structure/function of this important APOBEC deaminase family, with focuses on APOBEC3G and 3F (Apo3G and 3F) proteins and their interactions with cellular and viral ligands, using mainly structural biology, assisted by biophysics, molecular biology, and functional biochemistry.