The Molecular Basis of Diatom Adhesion and Motility

硅藻是一种单细胞藻类，占全球初级生物量产量的20%左右，因此具有巨大的生态重要性。许多硅藻具有非凡的能力，可以附着在水下任何自然和人造的表面上，并通过滑翔沿着表面移动。与贻贝的水下粘附机制相比，硅藻的粘附不依赖于含多巴的蛋白质。硅藻产生一种含有蛋白质、富含碳水化合物的黏附物质（AM），这种物质通过细胞壁上的一个特殊狭缝（称为缝）分泌出来，并以痕迹的形式沉积在基质上。AM提供必要的牵引力，而细胞运动的力量是由细胞内肌动蛋白-肌球蛋白系统产生的。肌动蛋白-肌球蛋白系统被假设通过细胞内和跨膜蛋白的连续体连接到细胞外AM路径。到目前为止，硅藻AM的分子组成和肌动蛋白-肌球蛋白运动系统的相关成分的特征仍然很差。基于我们最近的实验进展，本项目的目标是在已建立的硅藻粘附模式生物Craspedostauros australis中鉴定完整的粘附-运动复合物蛋白。该项目的工作将涉及蛋白质组学和生物信息学分析，分子遗传操作以及粘附和运动分析，以识别和功能表征硅藻粘附和运动相关的蛋白质。这一结果将为硅藻水下粘附的分子基础(a)和硅藻在表面上快速双向滑动的力的产生提供全新的见解。

Diatoms are unicellular algae that are responsible for ~20% of the global primary biomass production, and are thus of enormous ecological importance. Many diatoms have the remarkable ability to adhere to any natural and man-made surface underwater and move along the surfaces through gliding. In contrast to the well characterized mechanism for underwater adhesion of mussels, the adhesion of diatoms is independent of dopa-containing proteins. Diatoms produce a protein containing, carbohydrate-rich adhesive material (AM), which is secreted through a specialized slit in the cell wall (termed raphe) and deposited as trails on the substratum. The AM provides the necessary traction, while the force for cell motility is generated by an intracellular actin-myosin system. The actin-myosin system is hypothesized to be connected to the extracellular AM trails via a continuum of intracellular and transmembrane proteins. So far, the molecular composition of the diatom AM and the associated components of the actin-myosin based motility system has remained poorly characterized. Based our recent experimental advances we aim to identify in this project the complete set of proteins of the adhesion-motility complex in Craspedostauros australis, which is an established model organism for diatom adhesion. The work in this project will involve proteomics and bioinformatics analyses, molecular genetic manipulation, as well as adhesion and motility assays to identify and functionally characterize the proteins involved in diatom adhesion and motility. The results will provide fundamentally new insights into the molecular basis (a) for diatom underwater adhesion, and (b) for generating the force that enables the rapid bidirectional gliding of diatoms on surfaces.