Studies on the Protein-assisted Mechanism for Intracellular Membrane Contact Sites

这个项目将探索脂质在细胞器之间运动的机制。最近，强有力的证据表明，大多数脂质转运的帮助下发生的脂质转运蛋白，可以促进细胞器接触称为膜接触网站的形成。酵母的氧固醇结合同源物（奥什）蛋白是脂质转运蛋白的一个实例，其形成膜接触位点并充当细胞器之间脂质交换的极好模型。由于细胞可用于生产商业用途的化学品，因此了解脂质交换及其修饰方法可以改善化学品的生产。该项目将为研究人员提供科学培训，重点是从代表性不足的群体中征聘。项目概念和结果将用于少数民族服务高中暑期课程的教育推广，以及为公众开发动手蛋白质工程活动。奥什蛋白最初被认为是运输固醇，但最近被证明是重要的信号脂质，如磷脂酰肌醇的运输。该项目整合了实验和计算技术，以阐明膜接触位点的形成和探针脂质交换，首先研究奥什蛋白质的膜结合区域，然后全长蛋白质用于形成膜接触位点的机制。结合的脂质包装传感器的奥什蛋白模型膜（平面和弯曲）将探测使用增强的采样模拟，中子衍射，和高分辨率场循环核磁共振。Osh4与膜相互作用的其他结构域将被研究，重点是这种蛋白质可能如何构象变化，以促进膜接触位点。最终，全长Osh4蛋白形成膜接触位点和脂质转移的机制将通过开发用于双膜结合的新计算工具和使用场循环NMR和荧光技术来探索。该奖项由分子和细胞生物科学部的细胞动力学和功能组以及分子生物物理组共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will probe the mechanism of lipid movement between cellular compartments known as organelles. Recently, strong evidence indicates that most lipid transport occurs with the help of lipid transport proteins that can facilitate the formation of organelle contacts known as membrane contact sites. The oxysterol binding homologue (Osh) proteins of yeast are an example of lipid transport proteins that form membrane contact sites and serve as an excellent model for lipid exchange between organelles. Since cells can be used to produce chemicals for commercial use, understanding lipid exchange and ways to modify it could improve production of chemicals. This project will provide scientific training for researchers with focused recruitment from underrepresented groups. Project concepts and results will be used in educational outreach for minority-serving high school summer programs, courses, and developing hands-on protein engineering activities for the general public. Osh proteins were originally thought to transport sterols but have recently been shown to be important in the transport of signaling lipids, such as phosphatidylinositols. This project integrates experimental and computational techniques to elucidate membrane contact site formation and probe lipid exchange by first studying membrane-binding regions of Osh proteins and then the mechanism the full-length protein uses to form membrane contact sites. The binding of the lipid-packing sensor of Osh proteins to model membranes (planar and curved) will be probed using enhanced sampling simulations, neutron diffraction, and high-resolution field-cycling NMR. Other domains of Osh4 interacting with membranes will be studied with a focus on how this protein might conformationally change to facilitate membrane contact sites. Ultimately, the mechanism of the full-length Osh4 protein to form membrane contact sites and lipid transfer will be probed by developing new computational tools for dual-membrane binding and the use of field-cycling NMR and fluorescence techniques. This proposal is jointly funded by the Cellular Dynamics and Function cluster and Molecular Biophysics cluster in the Division of Molecular and Cellular Biosciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.