Molecular Architecture, Function, and Biogenesis of the Ventral Disc in Giardia

描述(申请人提供)：贾第鞭毛虫是一种分布广泛的人畜共患肠道寄生虫，是人类十大寄生虫之一，可引起严重的急性和慢性腹泻疾病。由于缺乏协调一致的研究努力，贾第鞭毛虫病已被指定为世界卫生组织(WHO)忽视的疾病。滋养体首先利用鞭毛的运动寻找合适的附着部位，然后通过腹盘(一种独特的微管结构)附着在绒毛上，从而避免蠕动流动，从而增殖和定居在小肠上。腹侧盘在发病机制上是至关重要的，因为它通过一种未知的机制介导了与肠道微绒毛的可逆附着。我们的主要关注点是评估体内和体外导致寄生虫附着的整个椎间盘构象变化所需的腹侧盘亚结构的功能。我们将首先确定鞭毛运动和侧脊(LC)接触对附着早期阶段的贡献(目标1)。然后，我们将把附着后期发生的各种盘状构象状态与亚结构的运动相关联(目标2)，并确定这些亚结构对产生附着所需的盘状构象的贡献(目标2)。最后，我们将根据有丝分裂后盘亚结构的组装，当两个背侧子盘组装和亲本腹侧盘被分解时，以及在摘除过程中，当两个新的子盘快速形成时，定义盘生物发生的阶段。这项工作将为我们分析光盘的结构和功能(目标1-2)提供信息。我们还将测试翻译后微管蛋白修饰在顺序地将盘相关蛋白招募到组装盘中的作用(目标3)。影响鞭毛运动、腹侧盘结构、盘生物发生或盘构象动力学的药物可直接或间接减少滋养体在宿主体内的附着，从而限制感染的起始程度。

DESCRIPTION (provided by applicant): Giardia is a widespread zoonotic intestinal parasite and is one of the ten major parasites of humans, causing significant acute and chronic diarrheal disease. Due to the lack of concerted research efforts, giardiasis has been designated a World Health Organization (WHO) neglected disease. To proliferate and colonize the small intestine, trophozoites first find suitable sites for attachment using flagellar motility, and then avoid peristaltic flow by attaching to the villi with the ventral disc, a unique microtubule structure. Te ventral disc is critical for pathogenesis in that it mediates reversible attachment to the intestinl microvilli via an undefined mechanism. Our primary focus is to evaluate the functions of ventral disc substructures that are required for overall disc conformational changes leading to parasite attachment in vivo and in vitro. We will first determine the contributions of flagellar motility an lateral crest (LC) contact to early stages of attachment (Aim 1). We will then correlate the various disc conformational states occurring in late stage attachment with movements of substructures (Aim 2), and determine the contributions of these substructures to generating disc conformations required for attachment (Aim 2). Finally, we will define the stages disc biogenesis with respect to the assembly of disc substructures after mitosis, when two dorsal daughter discs are assembled and the parental ventral disc is disassembled, and during excystation, when two new daughter discs are rapidly formed. This work will inform our analyses of disc structure and function (Aims 1-2). We will also test the role of posttranslational tubulin modifications in sequentially recruiting disc-associated proteins to the assembling disc (Aim 3). Drugs affecting flagellar motility, ventral disc structure, disc biogenesis, or disc conformational dynamics may directly or indirectly decrease trophozoite attachment in the host, and thus limit the initiation o extent of infection.