Cryo-electron microscopy(cryo-EM) provides a powerful tool to resolve the structure of biological macromolecules in natural state. One advantage of cryo-EM technology is that different conformation states of a protein...Cryo-electron microscopy(cryo-EM) provides a powerful tool to resolve the structure of biological macromolecules in natural state. One advantage of cryo-EM technology is that different conformation states of a protein complex structure can be simultaneously built, and the distribution of different states can be measured. This provides a tool to push cryo-EM technology beyond just to resolve protein structures, but to obtain the thermodynamic properties of protein machines. Here, we used a deep manifold learning framework to get the conformational landscape of Kai C proteins, and further obtained the thermodynamic properties of this central oscillator component in the circadian clock by means of statistical physics.展开更多
The genomic DNA of bacteria is highly compacted in one or a few bodies known as nucleoids. In order to understand the overall configuration and physiological activities of the cyanobacterial nucleoid under various gro...The genomic DNA of bacteria is highly compacted in one or a few bodies known as nucleoids. In order to understand the overall configuration and physiological activities of the cyanobacterial nucleoid under various growth conditions and the role(s) of each nucleoid protein in clock function, thylakoid membrane-associated nucleoids from the Synechococcus elongatus (se) PCC 7942 strain were isolated and purified in presence of spermidine at low salt concentrations by sucrose density gradient centrifugation. The sedimentation rates, protein/DNA composition and microscopic appearances as well as variation in structural components of clock proteins from the isolated nucleoids were compared under identical conditions. Microscopic appearances of the nucleoids were consistent with the sedimentation profiles. The nucleoid structure in the wild type was more tightly compacted than that in the KaiABC mutant strain. Western immunoblot analyses revealed that the KaiC was associated with the nucleoid fraction whereas maximum KaiA was localized in the cytosolic fraction, supposedly in association with the translation machinery.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 12090054)。
文摘Cryo-electron microscopy(cryo-EM) provides a powerful tool to resolve the structure of biological macromolecules in natural state. One advantage of cryo-EM technology is that different conformation states of a protein complex structure can be simultaneously built, and the distribution of different states can be measured. This provides a tool to push cryo-EM technology beyond just to resolve protein structures, but to obtain the thermodynamic properties of protein machines. Here, we used a deep manifold learning framework to get the conformational landscape of Kai C proteins, and further obtained the thermodynamic properties of this central oscillator component in the circadian clock by means of statistical physics.
文摘The genomic DNA of bacteria is highly compacted in one or a few bodies known as nucleoids. In order to understand the overall configuration and physiological activities of the cyanobacterial nucleoid under various growth conditions and the role(s) of each nucleoid protein in clock function, thylakoid membrane-associated nucleoids from the Synechococcus elongatus (se) PCC 7942 strain were isolated and purified in presence of spermidine at low salt concentrations by sucrose density gradient centrifugation. The sedimentation rates, protein/DNA composition and microscopic appearances as well as variation in structural components of clock proteins from the isolated nucleoids were compared under identical conditions. Microscopic appearances of the nucleoids were consistent with the sedimentation profiles. The nucleoid structure in the wild type was more tightly compacted than that in the KaiABC mutant strain. Western immunoblot analyses revealed that the KaiC was associated with the nucleoid fraction whereas maximum KaiA was localized in the cytosolic fraction, supposedly in association with the translation machinery.
