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Plasmodium Recombination of Machinery

机械的疟原虫重组

基本信息

批准号：
7834524
负责人：
Nirbhay Kumar
金额：
$ 40.49万
依托单位：
JOHNS HOPKINS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-06-05 至 2011-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7834524
关键词：
ATP phosphohydrolase Antigenic Diversity Antigenic Variation Bacterial Proteins Biochemical Cessation of life Chemicals Chromosomal Rearrangement Chromosomes Co-Immunoprecipitations Complementary DNA Culicidae DNA DNA Damage DNA Repair DNA Sequence Rearrangement Erythrocytes Eukaryota Foundations Future Gene Rearrangement Genes Genetic Genetic Recombination Genome Goals Growth Growth and Development function Homologous Gene Immune In Vitro Infection Lead Libraries Life Cycle Stages Link Malaria Mediating Mediator of activation protein Meiosis Messenger RNA Mesylates Mitosis Molecular Molecular Genetics Organism Parasites Phage Display Plasmodium Plasmodium falciparum Play Property Proteins Proteomics Reaction Recombinants Research Role Screening procedure Staging Surface Testing Transcript Vaccines Work base crosslink gene cloning homologous recombination improved insight knockout gene recombinase recombinational repair replication factor A response therapy development transmission process vaccine development

项目摘要

Malaria parasites, worldwide are responsible for 300-500 million new infections and 1-2 million deaths each year. An effective vaccine, however, remains elusive, partly due to antigenic diversity and the immune evasion strategies of the parasite. Recombination mechanisms are intimately linked with antigenic variation, a phenomenon of utmost significance for vaccine development against protozoan parasites like the malaria parasite. The long term objective of the proposed studies is to investigate mechanism(s) of genetic rearrangements associated with phenomenon like antigenic variation. An underlying tenet of the work proposed is that understanding the recombination mechanisms in Plasmodium will provide improved opportunities for the development of therapies. In other eukaryotes, homologous recombination (HR) plays a major role in chromosomal rearrangements, and Rad51 and Dmc1 proteins, the eukaryotic counterparts of bacterial RecA recombinase, are central molecules involved in HR during mitosis and meiosis. In eukaryotes, additional proteins like RPA and Rad54 functionally cooperate with Rad51 and mediate HR and the repair of damaged chromosomes. The hypothesis underlying proposed studies is that the Rad51 and other interacting proteins, as mediators of HR, play critical role(s) during growth and development of the parasite and facilitate gene rearrangements in P. falciparum. Molecular identification of Rad51 and Dmc1 homologues in P. falciparum and recent characterization of enzymatic properties of recombinant PfRad51, such as DNA strand exchange and ATPase activities, have strongly indicated a conserved functional role for PfRad51 in these organisms. We will test our hypothesis using biochemical as well as genetic approaches. Studies in the revised specific aims 1 and 2 will lead to in vitro characterization of the proteins involved in HR and thus probe into the biochemical basis of recombination and gene rearrangements in the parasites. PfRad51 gene knockout studies in the revised specific aim 3 will directly evaluate importance of PfRad51 in the erythrocytic growth of the parasite and analysis of repertoire of var gene transcripts. Moreover, studies on Dmc1 disruption (revised specific aim 3) will evaluate the role of meiosis specific recombinase during malaria transmission. The results of this study should be important in unraveling the recombination machinery and molecular and genetic basis for recombination and genetic rearrangements in P. falciparum.

全世界每年有 300-5 亿人感染疟原虫，并导致 1-200 万人死亡。然而，有效的疫苗仍然难以捉摸，部分原因是寄生虫的抗原多样性和免疫逃避策略。重组机制与抗原变异密切相关，这种现象对于针对疟疾寄生虫等原生动物寄生虫的疫苗开发至关重要。拟议研究的长期目标是研究与抗原变异等现象相关的基因重排机制。所提出的工作的基本原则是了解疟原虫的重组机制将为治疗的开发提供更好的机会。在其他真核生物中，同源重组 (HR) 在染色体重排中发挥着重要作用，Rad51 和 Dmc1 蛋白（细菌 RecA 重组酶的真核对应物）是有丝分裂和减数分裂过程中参与 HR 的中心分子。在真核生物中，RPA 和 Rad54 等其他蛋白质在功能上与 Rad51 配合，介导 HR 和受损染色体的修复。拟议研究的假设是，Rad51 和其他相互作用蛋白作为 HR 介质，在寄生虫的生长和发育过程中发挥关键作用，并促进恶性疟原虫中的基因重排。恶性疟原虫中 Rad51 和 Dmc1 同源物的分子鉴定以及重组 PfRad51 酶特性（例如 DNA 链交换和 ATP 酶活性）的最新表征，强烈表明 PfRad51 在这些生物体中具有保守的功能作用。我们将使用生化和遗传方法来检验我们的假设。修订后的具体目标 1 和 2 的研究将导致 HR 相关蛋白质的体外表征，从而探讨寄生虫重组和基因重排的生化基础。修订后的具体目标3中的PfRad51基因敲除研究将直接评估PfRad51在寄生虫红细胞生长中的重要性以及var基因转录本的全部分析。此外，对 Dmc1 破坏的研究（修订后的具体目标 3）将评估减数分裂特异性重组酶在疟疾传播过程中的作用。这项研究的结果对于揭示恶性疟原虫重组机制以及重组和遗传重排的分子和遗传基础具有重要意义。