Mechanistic target of rapamycin （mTOR） complex 1 （mTORC1） integrates signals from growth factors, cel- lular energy levels, stress and amino acids to control cell growth and proliferation through regulating trans-...Mechanistic target of rapamycin （mTOR） complex 1 （mTORC1） integrates signals from growth factors, cel- lular energy levels, stress and amino acids to control cell growth and proliferation through regulating trans- lation, autophagy and metabolism. Here we determined the cryo-electron microscopy structure of human mTORC1 at 4.4 A resolution. The mTORCI comprises a dimer of heterotrimer （mTOR-Raptor-mLST8） mediated by the mTOR protein. The complex adopts a hollow rhomboid shape with 2-fold symmetry. Notably, mTORC1 shows intrinsic conformational dynamics. Within the complex, the conserved N-terminal caspase- like domain of Raptor faces toward the catalytic cavity of the kinase domain of mTOR. Raptor shows no caspase activity and therefore may bind to TOS motif for sub- strate recognition. Structural analysis indicates that FKBP12-Rapamycin may generate steric hindrance forsubstrate entry to the catalytic cavity of mTORCI. The structure provides a basis to understand the assembly of mTORC1 and a framework to characterize the regu- latory mechanism of mTORC1 pathway.展开更多
KDM5B is a histone H3K4me2/3 demethylase. The PHD1 domain of KDM5B is critical for demethylation, but the mechanism underlying the action of this domain is unclear. In this paper, we observed that PHDIKDMSB interacts ...KDM5B is a histone H3K4me2/3 demethylase. The PHD1 domain of KDM5B is critical for demethylation, but the mechanism underlying the action of this domain is unclear. In this paper, we observed that PHDIKDMSB interacts with unmethylated H3K4me0. Our NMR structure of PHDIKDMSB in complex with H3K4me0 revealed that the binding mode is slightly different from that of other reported PHD fingers. The disruption of this interaction by double mutations on the residues in the interface （L325A/D328A） decreases the H3K4me2/3 demethylation activity of KDM5B in cells by approximately 50% and increases the transcriptional repression of tumor suppressor genes by approximately twofold. These findings imply that PHDIKDMSB may help maintain KDM5B at target genes to mediate the demethylation activities of KDM5B.展开更多
基金We thank staff members Biomedical Core Facility, Fudan University and National Center for Protein Science Shanghai for their help on Mass Spectrometry analyses. We thank the Tsinghua Cryo-EM Facility and High Performance Computation Facility of National Center for Protein Science Beijing for their support in cryo-EM data collection and processing. This work was supported by Grants from the National Natural Science Foundation of China （Grant Nos. U1432242, 31425008, 91419301）, Basic Research Project of Shanghai Science and Technology Commission （No. 12JC1402700）, the Program of Shanghai Subject Chief Scientist （,No. 14XD1400500）.
文摘Mechanistic target of rapamycin （mTOR） complex 1 （mTORC1） integrates signals from growth factors, cel- lular energy levels, stress and amino acids to control cell growth and proliferation through regulating trans- lation, autophagy and metabolism. Here we determined the cryo-electron microscopy structure of human mTORC1 at 4.4 A resolution. The mTORCI comprises a dimer of heterotrimer （mTOR-Raptor-mLST8） mediated by the mTOR protein. The complex adopts a hollow rhomboid shape with 2-fold symmetry. Notably, mTORC1 shows intrinsic conformational dynamics. Within the complex, the conserved N-terminal caspase- like domain of Raptor faces toward the catalytic cavity of the kinase domain of mTOR. Raptor shows no caspase activity and therefore may bind to TOS motif for sub- strate recognition. Structural analysis indicates that FKBP12-Rapamycin may generate steric hindrance forsubstrate entry to the catalytic cavity of mTORCI. The structure provides a basis to understand the assembly of mTORC1 and a framework to characterize the regu- latory mechanism of mTORC1 pathway.
文摘KDM5B is a histone H3K4me2/3 demethylase. The PHD1 domain of KDM5B is critical for demethylation, but the mechanism underlying the action of this domain is unclear. In this paper, we observed that PHDIKDMSB interacts with unmethylated H3K4me0. Our NMR structure of PHDIKDMSB in complex with H3K4me0 revealed that the binding mode is slightly different from that of other reported PHD fingers. The disruption of this interaction by double mutations on the residues in the interface （L325A/D328A） decreases the H3K4me2/3 demethylation activity of KDM5B in cells by approximately 50% and increases the transcriptional repression of tumor suppressor genes by approximately twofold. These findings imply that PHDIKDMSB may help maintain KDM5B at target genes to mediate the demethylation activities of KDM5B.
