Membrane Biophysics of African Trypanosomes

非洲锥虫的膜生物物理学

• 批准号: 391332795
• 负责人: Professor Dr. Markus Engstler, since 5/2021
• 金额: --
• 依托单位: Lehrstuhl für Zell- und Entwicklungsbiologie (Zoologie I)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/391332795?language=en
• 关键词: Membrane; Biophysics; African; Trypanosomes

Sleeping sickness poses a serious threat to humans and livestock in sub-Saharian Africa. It is caused by the trypanosome parasite, a unicellular flagellate and excellent model organism for research in the field ofmembrane biophysics.In the bloodstream of the host the trypanosome plasma membrane is covered with a dense, almost uniform coat of variant surface glycoproteins (VSGs). This highly dynamic surface coat is of vital importance because it protects the parasite from the immune system of the host. Due to its protein density the VSG coat constitutes a promising framework to study macromolecular crowding as well as allows comparative measurements with artificial model membranes. Endo- and exocytosis of diffusing VSG proteins are restricted to the flagellar pocket. This scenario is reminiscent of the so-called narrow escape problem (NEP) in two dimensions. The NEP is a common problem in biology and biophysics. It deals with Brownian particles confined to a given domain with reflecting borders and only a small opening where the particles are absorbed. Applying the currently available analytical solution of the NEP to calculate the time a VSG needs to find the flagellar pocket yields a clear discrepancy with experimental results. We will address the problem in two different ways. First, by measuring VSG dynamics in the external and internal membranes of T. brucei in vivo with single-molecule fluorescence microscopy and looking for non-Brownian components. We aim to identify the influence of physical effects like curvature-assisted sorting in contrast to active cell-dependent contributions. Choosing the well-characterized T. brucei as a model organism allows us to directly test contributions of active players, e.g. molecular motors, in knock-down experiments.Second, by challenging the theory of NE experimentally. In order to test the applicability of the analytical solution, we plan a systematic study in micro-patterned model membranes that allows us to vary geometric parameters and test the validity of the theoretical model in a wide phase space. Moreover, we aim to manipulate the in vivo geometry by knockdown of relevant structural proteins. It is the objective of this project to achieve both a deeper understanding of trypanosome physiology and the fundamental NEP. Ultimately, knowledge of the physical parameters underlying VSG dynamics could be the basis for the development of alternative trypanocide agents that aim to change these parameters and are thus not susceptible to induce resistance.

昏睡病对撒哈拉以南非洲的人类和牲畜构成严重威胁。它是由锥虫寄生虫引起的，锥虫寄生虫是一种单细胞鞭毛虫，是膜生物物理学研究的理想模式生物，在宿主的血流中，锥虫的质膜被一层致密的、几乎均匀的变异表面糖蛋白（VSG）所覆盖。这种高度动态的表面涂层至关重要，因为它保护寄生虫免受宿主免疫系统的侵害。由于其蛋白质密度的VSG涂层构成了一个有前途的框架，研究大分子拥挤，以及允许比较测量与人工模型膜。扩散VSG蛋白的内分泌和胞吐仅限于鞭毛袋。这种情况让人想起所谓的二维窄逃逸问题（NEP）。NEP是生物学和生物物理学中的一个常见问题。它涉及布朗粒子局限于一个给定的域反射边界和只有一个小的开口，在那里的粒子被吸收。应用目前可用的NEP的分析解决方案来计算的时间VSG需要找到鞭毛口袋产生了明显的差异与实验结果。我们将以两种不同的方式解决这个问题。首先，通过测量T.用单分子荧光显微镜观察体内布鲁氏菌并寻找非布朗组分。我们的目标是确定物理效应的影响，如曲率辅助分选，而不是积极的细胞依赖性的贡献。选择特征良好的T.布氏杆菌作为模式生物，使我们能够直接测试的积极球员，如分子马达，在击倒实验的贡献。为了测试的分析解决方案的适用性，我们计划在微图案化的模型膜，使我们能够改变几何参数和测试的有效性的理论模型在一个广泛的相空间进行系统的研究。此外，我们的目标是通过敲低相关结构蛋白来操纵体内几何形状。本项目的目标是实现对锥虫生理学和基本NEP的更深入理解。最终，VSG动力学的基础物理参数的知识可能是替代锥虫剂的发展，旨在改变这些参数，因此不容易诱导耐药性的基础。