题目： Single molecule studies of molecular structure and function in vitro and in vivo

时间：2017年3月24日（周五）下午1点

地点：北校区光电工程学院346会议室

报告人： Dr. Peiwu Qin（加州大学伯克利分校）

主持人：屈军乐 教授

摘要：Single molecule imaging has been used extensively to study molecular conformation, dynamics, and function. Here, I will demonstrate the application of single molecule imaging in ribosome dynamics in vitro and chromosome targeting in vivo. During protein synthesis, mRNA and tRNA are moved through the ribosome by the process of translocation. The small diameter of the mRNA entrance tunnel only permits unstructured mRNA to pass through. However, there are structured elements within mRNA that present a barrier for translocation that must be unwound. We discovered a new global conformational state of the ribosome by single molecule Förster resonance energy transfer and small angle X-ray scattering. In the presence of dnaX hairpin, the ribosomal subunits are driven into a hyper-rotated state and L1 stalk is predominantly in an open conformation. Imaging chromatin dynamics are mostly applicable to highly repetitive regions by CRISPR/Cas9 previously. We designed single-guide RNAs integrated with up to 16xMS2 binding motifs to enable robust fluorescent signal amplification. These engineered sgRNAs enable multicolor labeling with low-repeat-containing regions using a single sgRNA and non-repetitive regions with as few as four unique sgRNAs. We achieve tracking of native chromosome loci throughout the cell cycle and determine differential positioning……