Understanding The Structural Basis of APOBEC Functions

APOBEC（载脂蛋白B mrna编辑酶催化多肽）胞苷脱氨酶家族是一个对DNA/RNA的胞苷残基进行脱氨的酶家族。APOBEC蛋白具有重要的细胞功能和抗病毒活性，这也是近年来该研究领域受到高度关注的部分原因。APOBEC蛋白仅存在于脊椎动物中，而APOBEC3蛋白仅存在于灵长类动物中。通过结合和脱氨DNA/RNA， APOBEC酶实现了非常多样化的细胞功能。例如，APOBEC1 （Apo1）编辑参与脂质代谢的蛋白质的mRNA；AID在抗体成熟的体细胞超突变中起关键作用；APOBEC2 （Apo2）可能在心肌发育中起调节作用；Apo3蛋白，特别是Apo3G，可以限制重要的病毒病原体，包括人类免疫缺陷病毒（HIV）和乙型肝炎病毒（HBV），以及逆转录因子的流动性。因此，利用Apo3G和Apo3F的有效抗病毒活性是一种新的HIV治疗方法。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之前在APOBEC蛋白结构表征方面的成功扩展到APOBEC功能机制的结构基础研究，包括其抗病毒活性，特别关注Apo3G和Apo3F。该研究将为了解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HIV，免疫疾病和其他与APOBEC功能或功能障碍相关的疾病。载脂蛋白B mrna编辑酶催化多肽（APOBEC）家族胞苷脱氨酶仅存在于脊椎动物中。APOBEC核酸脱氨酶通过脱氨mRNA编码序列和ssDNA中的胞嘧啶修饰基因。它们的重要生物学作用包括脂质代谢、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）和乙型肝炎病毒（HBV），以及逆转录转座子。APOBEC蛋白具有重要的有益突变能力，如果其活性得不到严格调控，可能会对基因组的稳定性产生不利影响。对APOBEC功能分子机制的结构基础的了解，虽然目前仍知之甚少，但具有科学意义和直接的健康相关性。我们建议研究这一重要的APOBEC脱氨酶家族的结构/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，主要利用结构生物学，辅助生物物理学，分子生物学和功能生物化学。

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.