"Structure" magazine cover
On October 13, the well-known structural biology journal "Structure" published a cover article about the opening state of the molecular chaperone type 2 completed by the Sun Fei research group of the Institute of Biophysics of the Chinese Academy of Sciences and the Dong Zhiyang research group of the Institute of Microbiology The latest research results of crystal and electron microscope structure. The three co-first authors of the paper, Huo Yanwu, Hu Zhongjun, and Zhang Kai, respectively, made important contributions in protein purification crystal growth, electron microscopy image processing, and crystal structure analysis. Wang Li of the Institute of Microbiology provided biochemical experimental data for the samples .
Chaperonins (Chaperonins) is an ATP-dependent multi-subunit bicyclic complex that assists protein folding. Prior to this, the structure of the type 2 chaperonins nucleic acid binding function and the conformational changes in various links of the functional cycle They are not very thorough, and the most critical factor is the high-resolution structure without such molecular openings. This study effectively combined the three-dimensional reconstruction of cryo-electron microscopy and X-ray crystallography to obtain the structure of the first open-type molecular chaperone with a resolution of 3.7Ã…, which provides people with a functional cycle of understanding such molecules. Very critical structural information.
In this study, the type II chaperone ATcpnβ derived from the archaea Acidianus tengchongensis (AT) strain S5 was taken as the research object. The closed conformation of rATcpnβ at 14 Å resolution was obtained by three-dimensional reconstruction of negative staining electron microscope, and the conformation was found by analysis. The single subunit of the homologous crystal structure of the closed state reported previously is in good agreement; at the same time, the three-dimensional reconstruction method of the low temperature electron microscope is used to obtain the ATcpnβ apo state three-dimensional structure with a resolution of 8.8 Å and the ATP combined but unhydrolyzed state of 8.4 Å The three-dimensional structure of resolution is found to have an asymmetrical opening configuration, and the upper ring structure is closed than the lower ring structure (but the upper ring is not completely closed). This conformation is inferior to the previously reported homologous crystal structure, especially In the top domain.
In addition, the researchers obtained the crystal diffraction data of 3.7Å resolution of the open state of ATcpnβ combined with ADP through a lot of efforts. Using the low-temperature electron microscope structure as a model, the crystal structure was analyzed by molecular replacement method, and the first one with 9 The subsymmetrical crystal structure of the complete type 2 chaperone in the open state, while the atomic resolution crystal structure in the closed state with only 8 times symmetry before. The analysis revealed that the single subunit of the crystal structure was able to fit the opening conformation of rATcpnβ binding to ATP (but not hydrolyzed) very well. By comparing the open and closed conformations, the precise conformational changes of the type 2 chaperone during the process from ATP binding to ATP hydrolysis are observed more accurately-the entire subunit as a rigid body flips inward and the apical region relative to the equatorial domain ~ 30 degree rotation.
Previously, due to the lack of high-resolution crystal structure, some studies believed that the closure of the molecular chaperone was only related to the movement of the lid domain, while other studies believed that it was caused by the inward movement of the entire subunit. The high resolution obtained by this study The crystal structure resolves these disputes and provides the most accurate conformational change process.
In addition, the research results fully demonstrate the great advantages of combining the three-dimensional reconstruction of electron microscopy and X-ray crystallography for studying the structure of biological supramolecular complexes and explaining biological problems, which is also an important trend in the development of structural biology. Previously, due to the limitations of technical conditions, domestic structural biology research was mainly based on X-ray crystallography, and there were few successful examples of the combination of electron microscopy and crystallography; now, domestic investment in the three-dimensional reconstruction of electron microscopy has been huge. Research is undoubtedly a successful example in this situation.
Liquid Filling Equipment,Liquid Filling System,Digital Liquid Filling Machine,Automatic Drum Filler Machine
Changchun Rochiev Intelligent Equipment Manufacturing Co., Ltd. , https://www.rochiev-en.com