2018.05.21 Single-Molecule 3D Imaging for Studying Protein Structure, Dynamics and Mechanism
题 目：Single-Molecule 3D Imaging for Studying Protein Structure, Dynamics and Mechanism
报告人：Professor Gang Ren
The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley CA 94720-8197
主持人: 毛有东 研究员
Proteins have the unique ability to function specifically and efficiently, which is attained through its three-dimensional (3D) structures, flexibility and conformational changes. However, structural study on proteins with large-scale flexibility, dynamics, and heterogeneity is challenging by current techniques, including X-ray crystallography, nuclear magnetic resonance spectrum, small angle scattering and cryo-electron microscopy (cryo-EM) 3D reconstruction. A fundamental solution to study the flexible protein structure should be based on the structure determination of each individual protein molecule (without averaging from different protein molecules). Electron tomography (ET) provide a novel tool to image each individual molecule from a series of tilt angles at near atomic resolution. However, the signal obtained from an individual molecule is extremely weak due to radiation limitation. It has been decades that people believed a single molecule is impossible to be used to achieve a 3D with a resolution that can be used to understand the protein structural dynamics and mechanism. We re-investigated the possibility and proposed an approach, named individual-particle electron tomography (IPET) to improve the 3D structure resolution. This approach does not require a pre-given initial model or class averaging of multiple molecules, but can achieve single-molecule 3D structure at 1-2 nm resolution from negative staining sample, and 3-4 nm from cryo-EM sample. Through the comparison of the 3D structures from different molecules, the approach provides a new opportunity to reveal the dynamic character, equilibrium fluctuation, mechanism, aggregation and even structural changes in proteins during a chemical reaction or biological event.
Dr. Gang Ren, a career staff scientist and principal investigator at the Molecular Foundry, Lawrence Berkeley National Laboratory, USA. He received his BS in the department of theoretical physics at Lanzhou University in 1990. He received his MS training from Prof. Yishi Duan in same department in 1993. In 1997, he received PhD in Profs. Ke-Shin Kuo and Lian-mao Peng’s groups in the material physics department at University of Science and Tech Beijing. In the same year, he joined Profs. Alok Mitra and Mark Yeager groups in the department of cell biology at Scripps Research Institute, USA to start his postdoctory training in cryo-EM as a postdoctoral fellow supported by American Heart Association and California Aids Research program. In 2003, he worked with Prof. Wah Chiu as a research associate in the national center for Macromolecular imaging at Baylor College of Medicine, Houston, TX. In 2006, he started his independent research laboratory as a Keck Fellow and assistant research biochemist in the Biochemistry and biophysics department at UCSF. In 2010, he moved his laboratory to the Molecular foundry at Lawrence Berkeley National Laboratory, Berkeley, CA, US. His research focused on the protein dynamics by electron microscopy, which is supported by the funds from US Department of Energy, NIH R01s and Pharmaceutical companies. He published about 100 research papers in prestigious journals. He serves as an editorial board member of scientific reports and associate director of CASSS.