DNA and histone protein are important in the formation of nucleosomal arrays, which are the first packaging level of DNA into a more compact chromatin structure. To characterize the interactions of DNA and histone pro...DNA and histone protein are important in the formation of nucleosomal arrays, which are the first packaging level of DNA into a more compact chromatin structure. To characterize the interactions of DNA and histone proteins, we reconstitute nucleosomes using lambda DNA and whole histone proteins by dialysis and perform direct atomic force microscopy （AFM） imaging. Compared with non-specific DNA and histone binding, nucleosomes are formed within the assembled “beads-on-a-string” nucleosomal array by dialysis. These observations facilitate the establishment of the molecular mechanisms of nucleosome and demonstrate the capability of AFM for protein-DNA interaction analysis.展开更多
Lipid rafts are a dynamic microdomain structure found in recent years, enriched in sphin- golipids, cholesterol and particular proteins. The change of structure and function of lipid rafts could result in many disease...Lipid rafts are a dynamic microdomain structure found in recent years, enriched in sphin- golipids, cholesterol and particular proteins. The change of structure and function of lipid rafts could result in many diseases. In this work, the monolayer miscibility behavior of mixed systems of Egg-Sphingomyelin （ESM） with 1, 2-dioleoyl-sn-glycero-3-phosphocholine was in- vestigated in terms of mean surface area per molecule and excess molecular area AAex at certain surface pressure, surface pressure and excess surface pressure Arcex at certain mean molecular area. The stability and compressibility of the mixed monolayers was assessed by the parameters of surface excess Gibbs free energy AGex, excess Helmholtz energy AHex and elasticity. Thermodynamic analysis indicates AAex and ATrex in the binary systems with positive deviations from the ideal behavior, suggesting repulsive interaction. The max- imum of AGex and AHex was at the molar fraction of ESM of 0.6, demonstrating the mixed monolayer was more unstable. The repulsive interaction induced phase separation in the monolayer.展开更多
The function of the herpes simplex virus type 1 （HSV-1） UL4 protein is still elusive. Our objective is to investigate the subcellular transport mechanism of the UL4 protein. In this study, fluorescence microscopy wa...The function of the herpes simplex virus type 1 （HSV-1） UL4 protein is still elusive. Our objective is to investigate the subcellular transport mechanism of the UL4 protein. In this study, fluorescence microscopy was employed to investigate the subcellular localization of UL4 and characterize the transport mechanism in living cells. By constructing a series of deletion mutants fused with enhanced yellow fluorescent protein （EYFP）, the nuclear export signals （NES） of UL4 were for the first time mapped to amino acid residues 178 to 186. In addition, the N-terminal 19 amino acids are identified to be required for the granule-like cytoplasmic pattem of UL4. Furthermore, the UL4 protein was demonstrated to be exported to the cytoplasm through the NES in a chromosomal region maintenance 1 （CRM1）-dependent manner involving RanGTP hydrolysis展开更多
Exposure to cigarette smoke is a major risk factor for cancer and cardiovascular disease. Thrombosis is regarded as the main reason for smoking-related car- diovascular disease. However, the detail mechanism of how sm...Exposure to cigarette smoke is a major risk factor for cancer and cardiovascular disease. Thrombosis is regarded as the main reason for smoking-related car- diovascular disease. However, the detail mechanism of how smoking promotes thrombosis is not fully under- stood. In this work, we investigated the impacts of one major cigarette carcinogens 4-（methylnitrosamino）-l-（3- pyridyl）-l-butanone （NNK） as well as its metabolite 4-（methylnitrosamino）- 1-（3-pyridyl）- 1-butanol （NNAL） on a key process in thrombosis regulation： thrombin- thrombomodulin （TM） binding. Atomic force microscopy based single-molecule force spectroscopy was applied to measure both in vitro and in vivo binding force of thrombin to TM in the absence and presence of NNK and NNAL respectively. The results revealed that NNK and NNAL can reduce the binding probability of TM and thrombin. The inhibition effect and underlying mechanism was further studied by molecular simulation. As indicated by our results, the cigarette carcinogens could cause a higher risk of thrombosis through the disruption of TM- thrombin interaction.展开更多
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.11274374）, the National Basic Research Program of China （No.2009CB930704）, and the Basic Scientific Research Foundation of China Agricultural University （No.2012QJ026）.
文摘DNA and histone protein are important in the formation of nucleosomal arrays, which are the first packaging level of DNA into a more compact chromatin structure. To characterize the interactions of DNA and histone proteins, we reconstitute nucleosomes using lambda DNA and whole histone proteins by dialysis and perform direct atomic force microscopy （AFM） imaging. Compared with non-specific DNA and histone binding, nucleosomes are formed within the assembled “beads-on-a-string” nucleosomal array by dialysis. These observations facilitate the establishment of the molecular mechanisms of nucleosome and demonstrate the capability of AFM for protein-DNA interaction analysis.
文摘Lipid rafts are a dynamic microdomain structure found in recent years, enriched in sphin- golipids, cholesterol and particular proteins. The change of structure and function of lipid rafts could result in many diseases. In this work, the monolayer miscibility behavior of mixed systems of Egg-Sphingomyelin （ESM） with 1, 2-dioleoyl-sn-glycero-3-phosphocholine was in- vestigated in terms of mean surface area per molecule and excess molecular area AAex at certain surface pressure, surface pressure and excess surface pressure Arcex at certain mean molecular area. The stability and compressibility of the mixed monolayers was assessed by the parameters of surface excess Gibbs free energy AGex, excess Helmholtz energy AHex and elasticity. Thermodynamic analysis indicates AAex and ATrex in the binary systems with positive deviations from the ideal behavior, suggesting repulsive interaction. The max- imum of AGex and AHex was at the molar fraction of ESM of 0.6, demonstrating the mixed monolayer was more unstable. The repulsive interaction induced phase separation in the monolayer.
基金the Major State Basic Research Development Program of China(2010CB530105 and 2011CB504802)the National Natural Science Foundation of China(30900059,30870120 and 81000736)the Start-up Fund of the Hundred Talents Program of the Chinese Academy of Sciences(20071010-141)
文摘The function of the herpes simplex virus type 1 （HSV-1） UL4 protein is still elusive. Our objective is to investigate the subcellular transport mechanism of the UL4 protein. In this study, fluorescence microscopy was employed to investigate the subcellular localization of UL4 and characterize the transport mechanism in living cells. By constructing a series of deletion mutants fused with enhanced yellow fluorescent protein （EYFP）, the nuclear export signals （NES） of UL4 were for the first time mapped to amino acid residues 178 to 186. In addition, the N-terminal 19 amino acids are identified to be required for the granule-like cytoplasmic pattem of UL4. Furthermore, the UL4 protein was demonstrated to be exported to the cytoplasm through the NES in a chromosomal region maintenance 1 （CRM1）-dependent manner involving RanGTP hydrolysis
基金supported by the National Basic Research Program of China (2013CB933701, 2013CB933704)the National Natural Science Foundation of China (21127901)
文摘Exposure to cigarette smoke is a major risk factor for cancer and cardiovascular disease. Thrombosis is regarded as the main reason for smoking-related car- diovascular disease. However, the detail mechanism of how smoking promotes thrombosis is not fully under- stood. In this work, we investigated the impacts of one major cigarette carcinogens 4-（methylnitrosamino）-l-（3- pyridyl）-l-butanone （NNK） as well as its metabolite 4-（methylnitrosamino）- 1-（3-pyridyl）- 1-butanol （NNAL） on a key process in thrombosis regulation： thrombin- thrombomodulin （TM） binding. Atomic force microscopy based single-molecule force spectroscopy was applied to measure both in vitro and in vivo binding force of thrombin to TM in the absence and presence of NNK and NNAL respectively. The results revealed that NNK and NNAL can reduce the binding probability of TM and thrombin. The inhibition effect and underlying mechanism was further studied by molecular simulation. As indicated by our results, the cigarette carcinogens could cause a higher risk of thrombosis through the disruption of TM- thrombin interaction.
