APOBEC proteins and uracil in retrovirus restriction

逆转录病毒限制中的 APOBEC 蛋白和尿嘧啶

• 批准号: 7004740
• 负责人: Reuben S Harris
• 金额: $ 27.08万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7004740
• 关键词: DNA repair; Retroviridae; aminoacid; aminohydrolases; carcinogenesis; clinical research; cytidine; enzyme activity; gene expression; host organism interaction; human genetic material tag; human immunodeficiency virus 1; human subject; protein structure function; site directed mutagenesis; uracil; virus DNA; virus infection mechanism; virus protein; virus replication

DESCRIPTION (provided by applicant): The cellular APOBEC3F and -3G proteins restrict the ability of retroviruses, including HIV-1, to successfully infect human cells. This novel innate immune defense occurs by APOBEC-catalyzed deamination of nascent cytosine residues in the cDNA strand of a replicating retrovirus. At least four mechanistic steps are required for APOBEC-dependent retroviral restriction. First, these APOBEC proteins must avoid the HIV-1 counterdefense protein Vif, which can mediate their destruction. Second, the APOBECs must incorporate into viral particles. Third, upon retroviral reverse transcription the APOBECs deaminate nascent cDNA cytosines. This produces uracil residues within the retroviral DNA, which are regarded as lesions by cellular DNA repair pathways. Thus, the fourth step may involve both the replication and fixation of minus strand uracils as plus strand adenines (hypermutation) and also the recognition and processing of uracils by other unidentified cellular enzymes. The latter event is likely to block the retrovirus from integrating. This proposal will better define these steps by delineating the key APOBEC protein domains and amino acid residues required for the first three steps. A powerful combination of model microbial, biochemical and retroviral systems will be used and complemented with somatic cell genetic techniques. These systems will be further applied to identify cellular DNA repair enzymes, likely base excision repair proteins, responsible for the fourth step. Finally, the identity and relative contributions of the APOBEC proteins that inhibit HIV-1 infection in the primary human viral reservoirs will be defined. Together the proposed studies will result in a fundamental understanding of the mechanism of APOBEC-dependent retroviral restriction. This will assist the rational design of therapies that could potentially attenuate HIV-1 by modulating the cellular APOBEC defense and the retroviral Vif counterdefense. The consequences of failing to appreciate these fundamental steps could be catastrophic as mis-regulation/expression of APOBEC family members has been associated with carcinogenesis.

描述（由申请人提供）：细胞APOBEC3F和-3G蛋白限制了包括HIV -1在内的逆转录病毒成功感染人类细胞的能力。这种新型的先天免疫防御是通过Apobec催化的重复逆转录病毒cDNA链中新生胞嘧啶残基的脱氨酸。至少需要四个机械步骤来依赖APOBEC逆转录病毒限制。首先，这些APOBEC蛋白必须避免使用HIV-1反防御蛋白VIF，这可以介导其破坏。其次，apobecs必须掺入病毒颗粒中。第三，在逆转录病毒逆转录时，apobecs脱氨酸新生cDNA胞嘧啶。这会在逆转录病毒DNA中产生尿嘧啶残基，该残基被细胞DNA修复途径视为病变。因此，第四步可能涉及减去尿酸的复制和固定为加上链腺苷（超松蛋白），以及其他未鉴定的细胞酶对尿嘧啶的识别和加工。后一个事件可能会阻止逆转录病毒集成。 该建议将通过描述前三个步骤所需的关键APOBEC蛋白结构域和氨基酸残基来更好地定义这些步骤。模型微生物，生化和逆转录病毒系统的强大组合将使用并与体细胞遗传技术相辅相成。这些系统将进一步应用于鉴定细胞DNA修复酶，即可能的碱性切除修复蛋白，负责第四步。最后，将定义APOBEC蛋白抑制HIV-1感染的APOBEC蛋白的身份和相对贡献。拟议的研究一起将导致对APOBEC依赖性逆转录病毒限制机制的基本理解。这将有助于通过调节细胞APOBEC防御和逆转录病毒VIF反防御的疗法的合理设计，这些疗法有可能减弱HIV-1。不欣赏这些基本步骤的后果可能是灾难性的，因为Apobec家族成员的错误调节/表达与致癌作用有关。