The role of lysine methylation in regulating the motility of Toxoplasma gondii

赖氨酸甲基化在调节弓形虫运动中的作用

• 批准号: 8437959
• 负责人: Ke Hu
• 金额: $ 39.51万
• 依托单位: TRUSTEES OF INDIANA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-12-01 至 2017-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8437959
• 关键词: ATP Hydrolysis; Acquired Immunodeficiency Syndrome; Acute; Adverse effects; Affect; Apical; Binding Proteins; Biological Assay; Cell Nucleus; Cells; Chromatin; Complex; Cytoplasm; Defect; Development; Disease; Drug Targeting; Drug resistance; Encephalitis; Environment; Fetus; Gene Expression; Gene Targeting; Genetic Transcription; Goals; Growth; Histone-Lysine N-Methyltransferase; Histones; Human; Imaging technology; Immune system; In Vitro; Infection; Lysine; Lytic Phase; Mediating; Methylation; Methyltransferase; Motor; Motor Activity; Myosin ATPase; Nature; Parasites; Pathogenesis; Pathway interactions; Patients; Pharmaceutical Preparations; Physiology; Population; Proteins; Proteomics; Regulation; Role; Shotguns; Signal Transduction; Signal Transduction Pathway; Site; Testing; Time; Tissues; Toxoplasma gondii; Toxoplasmosis; Transcriptional Regulation; Translations; base; cell motility; comparative; design; in vivo; insight; killings; novel; prevent; protein distribution; public health relevance; single molecule

DESCRIPTION (provided by applicant): Toxoplasmosis is caused by the parasite Toxoplasma gondii. The infection of T. gondii can cause severe tissue damages when the immune system is compromised (such as in AIDS patients) or underdeveloped (such as in fetuses). If not treated in time, uncontrolled T. gondii proliferation (i.e. acute toxoplasmosis) will have devastating consequences, including the development of toxoplasmic encephalitis. Current medications for treating toxoplasmosis drugs block growth but do not kill the parasite; thus they must be taken for long periods, during which severe side-effects routinely develop. For infection with drug resistant parasite strains, the treatment options either are very limited or do not exist. New drug that target parasites more specifically are therefore desperately needed. To cause disease, T. gondii must reiterate its lytic cycle through host cell invasion, replication, and parasite egress. The successful completion of this cycle requires that the parasite sense changes in environmental conditions and switch between non-motile and motile states, accordingly. Despite its importance in parasite physiology, the signal relay that regulates this switch is poorly understood. Recently we discovered a previously unknown mechanism of regulating cell motility in T. gondii, mediated by a novel protein lysine methyltransferase, AKMT (for Apical complex lysine (K) methyltransferase). When AKMT is absent, the parasite remains immotile. Both invasion and egress, and thus the complete lytic cycle, are inhibited. If we understood the detailed nature of this inhibition, then it could be exploited to develop new parasite specific drugs. Towards that goal, three major questions need to be answered. 1) Is the motor itself crippled in the absence of AKMT? 2) Whether or not the motor is crippled, are other essential components of the motility apparatus dependent on methylation? 3) Why, in functional terms, is methylation required for each sensitive component (i.e., required for proper assembly of the apparatus?; for ATP hydrolysis or other catalytic activity?; for correct subcellular localization?) To answer these critical questions, we have designed the following three specific aims: Aim1-Determine if AKMT directly regulates the activity of the myosin motor complex; Aim2- Identify AKMT targets; and Aim3- Determine the function and spatial-temporal distribution of the AKMT targets. We will use a multi-faceted approach to pursue our aims, combining proteomics, state of the art imaging technologies, biophysical assays and targeted gene disruption.

描述（由申请人提供）：弓形虫病是由寄生虫弓形虫引起的。当免疫系统受损（例如艾滋病患者）或发育不全（例如胎儿）时，弓形虫感染可导致严重的组织损伤。如果不及时治疗，不受控制的弓形虫增殖（即急性弓形虫病）将产生毁灭性后果，包括发展为弓形虫脑炎。目前治疗弓形虫病的药物会阻止寄生虫生长，但不能杀死寄生虫；因此，它们必须长期服用，在此期间通常会产生严重的副作用。对于耐药寄生虫菌株感染，治疗选择要么非常有限，要么根本不存在。因此，迫切需要更具体地针对寄生虫的新药。为了引起疾病，弓形虫必须通过宿主细胞入侵、复制和寄生虫排出来重复其裂解周期。 该周期的成功完成需要寄生虫感知环境条件的变化并相应地在非运动状态和运动状态之间切换。尽管调节这种开关的信号继电器在寄生虫生理学中很重要，但人们对它知之甚少。最近，我们发现了一种以前未知的弓形虫细胞运动调节机制，该机制由一种新型蛋白质赖氨酸甲基转移酶 AKMT（顶端复合赖氨酸 (K) 甲基转移酶）介导。当 AKMT 缺失时，寄生虫保持不动。入侵和出口，以及整个裂解周期，都被抑制。如果我们了解这种抑制的详细性质，那么就可以利用它来开发新的寄生虫特异性药物。为了实现这一目标，需要回答三个主要问题。 1) 如果没有 AKMT，电机本身是否会损坏？ 2）无论马达是否受损，运动装置的其他重要组成部分是否依赖于甲基化？ 3) 从功能角度来说，为什么每个敏感组件都需要甲基化（即，正确组装装置所需？；ATP 水解或其他催化活性？；正确的亚细胞定位？）为了回答这些关键问题，我们有设计了以下三个具体目标： Aim1-确定AKMT是否直接调节肌球蛋白运动复合体的活性；目标 2- 识别 AKMT 目标；目标3-确定AKMT目标的功能和时空分布。我们将采用多方面的方法来实现我们的目标，结合蛋白质组学、最先进的成像技术、生物物理测定和靶向基因破坏。