Hong-Wei Wang’s group published a research article in Nature Communications on making a new record of the smallest size of protein solved by single particle cryo-EM at near atomic resolution
Professor Hong-Wei Wang’s group at Tsinghua University, School of Life Sciences published a research article in Nature Communications on 3rd June, 2019, entitled "Single particle cryo-EM reconstruction of 52 kDa streptavidin at 3.2 Angstrom resolution". This work makes a new record of the smallest size of protein solved by single particle cryo-EM at near atomic resolution. At the same time, this work provides evidence for the critical influence of air-water interface for protein particle behavior in cryo-EM sample.
Single particle analysis of 52 kDa streptavidin
In the past few years, single particle cryo-EM analysis has raised dramatically than any other techniques in structural biology. The current method is feasible to obtain the 3D structure of well-behaved macromolecules with a molecular weight higher than 300 kDa at ~3 A resolution regularly. However, it remains challenging to obtain the high-resolution structures of molecules smaller than 200 kDa mainly due to the lack of contrast. Recent developments in new apparatuses, especially the Volta phase plate (VPP), have been increasingly used in cryo-EM. VPP could boost the image contrast significantly and keep enough high-resolution signal for three dimensional reconstructions at the same time. To further apply VPP to small molecular weight protein structural studies, it still requires more detailed characterizations on its behavior.
In this work, Hong-Wei Wang’s group apply previous developed Cs-corrector-VPP coupled cryoEM （Fan et al., 2017）and monolayer single-crystalline graphene grid （Zhang et al., 2017）to study the 52 kDa streptavidin protein supported on graphene grids and obtained both the apo-SA and biotin-bound SA structures at near-atomic resolution. So far, this is the smallest protein solved by SPA at near-atomic resolution. They further demonstrated that the method has the potential to determine the structures of molecules as small as 39 kDa. Besides, they find that graphene avoiding the adsorption of proteins onto the air-water interface is helpful for maintaining the high-resolution structural information. These results strongly support the air-water interface hypothesis and suggest that their method is capable for a more widely use in cryoEM.
Professor Hong-Wei Wang and Professor Jianlin Lei are the co-corresponding authors of this work. Ph.D. student Xiao Fan, from CLS program in Tsinghua University School of Life Sciences and Post-doc Jia Wang are the co-first authors. Post-doc Xing Zhang, Ph.D. student Zi Yang and Post-doc Xing Zhang contributed to this work. Graphene grids are provided by Ph.D. student Jin-Can Zhang from Professor Hai-Lin Peng’s group in Peking University Academy for Advanced Interdisciplinary Studies. This work is supported by Tsinghua University Branch of the National Protein Science Facility. All data collection is supported by Tsinghua University cryo-EM facility platform. Data processing is supported by High-Performance Computation platforms. This work is supported by grant (2016YFA0501100 to H.W. and J.L.) from the Ministry of Science and Technology of China, grant (Z161100000116034 to H.W.) from the Beijing Municipal Science & Technology Commission.
Original Publication:
Reference:
[1] Fan X, Zhao L, Liu C, et al. Near-Atomic Resolution Structure Determination in Over-Focus with Volta Phase Plate by Cs-Corrected Cryo-EM[J]. Structure, 2017, 25(10):1623.
[2] Zhang J , Lin L , Sun L , et al. Single Crystals: Clean Transfer of Large Graphene Single Crystals for High‐Intactness Suspended Membranes and Liquid Cells[J]. Advanced Materials, 2017, 29(26):1700639.
