Western equine encephalitis virus(WEEV)is an arbovirus that historically caused large outbreaks of encephalitis throughout the Americas.WEEV binds protocadherin 10(PCDH10)as a receptor,and highly virulent ancestral WE...Western equine encephalitis virus(WEEV)is an arbovirus that historically caused large outbreaks of encephalitis throughout the Americas.WEEV binds protocadherin 10(PCDH10)as a receptor,and highly virulent ancestral WEEV strains also bind low-density lipoprotein receptor(LDLR)-related proteins.As WEEV declined as a human pathogen in North America over the past century,isolates have lost the ability to bind mammalian receptors while still recognizing avian receptors.To explain shifts in receptor dependencies and assess the risk of WEEV re-emergence,we determined cryoelectron microscopy structures of WEEV bound to human PCDH10,avian PCDH10,and human very-low-density lipoprotein receptor(VLDLR).We show that one to three E2 glycoprotein substitutions are sufficient for a nonpathogenic strain to regain the ability to bind mammalian receptors.A soluble VLDLR fragment protects mice from lethal challenge by a virulent ancestral WEEV strain.Because WEEV recently re-emerged in South America after decades of inactivity,our findings have important implications for outbreak preparedness.展开更多
The rise of quantum computing has prompted the interest in the field of cryogenic electronics.Carbon-based materials hold great promise in the area of cryogenic electronics due to their excellent material properties a...The rise of quantum computing has prompted the interest in the field of cryogenic electronics.Carbon-based materials hold great promise in the area of cryogenic electronics due to their excellent material properties and emergent quantum effects.This paper introduces the advantages of carbon-based materials for cryogenic applications and reviews recent progress in carbon nanotubes and graphene for logic devices,sensors and novel quantum devices at cryogenic tempera-tures.Finally,the main challenges and extensive prospects for the fur-ther development of carbon-based cryoelectronics are summarized.展开更多
A three-dimensional （3D） reconstruction of icosahedral virus is carried out by the icosahedral symmetry-adapted function （ISAF） method in spherical coordinates. In order to reduce the influence of noise, it is bet...A three-dimensional （3D） reconstruction of icosahedral virus is carried out by the icosahedral symmetry-adapted function （ISAF） method in spherical coordinates. In order to reduce the influence of noise, it is better to use the basis functions that have identical symmetry with the object reconstructed. It is verified that the ISAF method has stronger ability to reduce the influence of noise to grain the resolution better than that of the conventional method by the simulation of 3D reconstruction.展开更多
Diatoms,a group of prevalent marine algae,contribute significantly to global primary productivity.Their substantial biomass is linked to enhanced absorption of blue-green light underwater,facilitated by fucoxanthin ch...Diatoms,a group of prevalent marine algae,contribute significantly to global primary productivity.Their substantial biomass is linked to enhanced absorption of blue-green light underwater,facilitated by fucoxanthin chlorophyll(Chl)a/c-binding proteins(FCPs),which exhibit oligomeric diversity across diatom species.Using mild clear native PAGE analysis of solubilized thylakoid membranes,we displayed monomeric,dimeric,trimeric,tetrameric,and pentameric FCPs in diatoms.Mass spectrometry analysis revealed that each oligomeric FCP has a specific protein composition,and together they constitute a large Lhcf family of FCP antennas.In addition,we resolved the structures of the Thalassiosira pseudonana FCP(Tp-FCP)homotrimer and the Chaetoceros gracilis FCP(Cg-FCP)pentamer by cryoelectron microscopy at 2.73-Åand 2.65-Åresolution,respectively.The distinct pigment compositions and organizations of various oligomeric FCPs affect their blue-green light-harvesting,excitation energy transfer pathways.Compared with dimeric and trimeric FCPs,the Cg-FCP tetramer and Cg-FCP pentamer exhibit stronger absorption by Chl c,redshifted and broader Chl a fluorescence emission,and more robust circular dichroism signals originating from Chl a-carotenoid dimers.These spectroscopic characteristics indicate that Chl a molecules in the Cg-FCP tetramer and Cg-FCP pentamer are more heterogeneous than in both dimers and the Tp-FCP trimer.The structural and spectroscopic insights provided by this study contribute to a better understanding of the mechanisms that empower diatoms to adapt to fluctuating light environments.展开更多
Photosystem I(PSI)is a large protein supercomplex that catalyzes the light-dependent oxidation of plastocyanin(or cytochrome c6)and the reduction of ferredoxin.This catalytic reaction is realized by a transmembrane el...Photosystem I(PSI)is a large protein supercomplex that catalyzes the light-dependent oxidation of plastocyanin(or cytochrome c6)and the reduction of ferredoxin.This catalytic reaction is realized by a transmembrane electron transfer chain consisting of primary electron donor(a special chlorophyll(Chl)pair)and electron acceptors A_(0),A_(1),and three Fe_(4)S_(4) clusters,F_(X),F_(A),and F_(B).Here we report the PSI structure from a Chl d-dominated cyanobacterium Acaryochloris marina at 3.3Åresolution obtained by single-particle cryo-electron microscopy.The A.marina PSI exists as a trimer with three identical monomers.Surprisingly,the structure reveals a unique composition of electron transfer chain in which the primary electron acceptor A_(0) is composed of two pheophytin a rather than Chl a found in any other well-known PSI structures.A novel subunit Psa27 is observed in the A.marina PSI structure.In addition,77 Chls,13α-carotenes,two phylloquinones,three Fe-S clusters,two phosphatidyl glycerols,and one monogalactosyl-diglyceride were identified in each PSI monomer.Our results provide a structural basis for deciphering the mechanism of photosynthesis in a PSI complex with Chl d as the dominating pigments and absorbing far-red light.展开更多
文摘Western equine encephalitis virus(WEEV)is an arbovirus that historically caused large outbreaks of encephalitis throughout the Americas.WEEV binds protocadherin 10(PCDH10)as a receptor,and highly virulent ancestral WEEV strains also bind low-density lipoprotein receptor(LDLR)-related proteins.As WEEV declined as a human pathogen in North America over the past century,isolates have lost the ability to bind mammalian receptors while still recognizing avian receptors.To explain shifts in receptor dependencies and assess the risk of WEEV re-emergence,we determined cryoelectron microscopy structures of WEEV bound to human PCDH10,avian PCDH10,and human very-low-density lipoprotein receptor(VLDLR).We show that one to three E2 glycoprotein substitutions are sufficient for a nonpathogenic strain to regain the ability to bind mammalian receptors.A soluble VLDLR fragment protects mice from lethal challenge by a virulent ancestral WEEV strain.Because WEEV recently re-emerged in South America after decades of inactivity,our findings have important implications for outbreak preparedness.
基金supported by the National Key Research&Develop-ment Program(Grant No.2022YFB4401601)Natural Science Foundation of China(62225101,12374035 and 11974026).
文摘The rise of quantum computing has prompted the interest in the field of cryogenic electronics.Carbon-based materials hold great promise in the area of cryogenic electronics due to their excellent material properties and emergent quantum effects.This paper introduces the advantages of carbon-based materials for cryogenic applications and reviews recent progress in carbon nanotubes and graphene for logic devices,sensors and novel quantum devices at cryogenic tempera-tures.Finally,the main challenges and extensive prospects for the fur-ther development of carbon-based cryoelectronics are summarized.
文摘A three-dimensional （3D） reconstruction of icosahedral virus is carried out by the icosahedral symmetry-adapted function （ISAF） method in spherical coordinates. In order to reduce the influence of noise, it is better to use the basis functions that have identical symmetry with the object reconstructed. It is verified that the ISAF method has stronger ability to reduce the influence of noise to grain the resolution better than that of the conventional method by the simulation of 3D reconstruction.
基金National Key R&D Program of China(2021YFA1300403 and 2019YFA0906300)Youth Innovation Promotion Association of CAS(2020081)+4 种基金CAS Interdisciplinary Innovation Team(JCTD-2020-06)CAS Project for Young Scientists in Basic Research(YSBR-004)National Natural Science Foundation of China(32222007)Innovation Platform for Academicians of Hainan Province(2022YSCXTD0005)Science&Technology Specific Project in Agricultural High-tech Industrial Demonstration Area of the Yellow River Delta(2022SZX12).
文摘Diatoms,a group of prevalent marine algae,contribute significantly to global primary productivity.Their substantial biomass is linked to enhanced absorption of blue-green light underwater,facilitated by fucoxanthin chlorophyll(Chl)a/c-binding proteins(FCPs),which exhibit oligomeric diversity across diatom species.Using mild clear native PAGE analysis of solubilized thylakoid membranes,we displayed monomeric,dimeric,trimeric,tetrameric,and pentameric FCPs in diatoms.Mass spectrometry analysis revealed that each oligomeric FCP has a specific protein composition,and together they constitute a large Lhcf family of FCP antennas.In addition,we resolved the structures of the Thalassiosira pseudonana FCP(Tp-FCP)homotrimer and the Chaetoceros gracilis FCP(Cg-FCP)pentamer by cryoelectron microscopy at 2.73-Åand 2.65-Åresolution,respectively.The distinct pigment compositions and organizations of various oligomeric FCPs affect their blue-green light-harvesting,excitation energy transfer pathways.Compared with dimeric and trimeric FCPs,the Cg-FCP tetramer and Cg-FCP pentamer exhibit stronger absorption by Chl c,redshifted and broader Chl a fluorescence emission,and more robust circular dichroism signals originating from Chl a-carotenoid dimers.These spectroscopic characteristics indicate that Chl a molecules in the Cg-FCP tetramer and Cg-FCP pentamer are more heterogeneous than in both dimers and the Tp-FCP trimer.The structural and spectroscopic insights provided by this study contribute to a better understanding of the mechanisms that empower diatoms to adapt to fluctuating light environments.
基金The project was funded by the National Key R&D Program of China(2020YFA0907600,2017YFA0503700,2017YFA0504803,2018YFA0507700,2019YFA0906300)the Strategic Priority Research Program of CAS(XDA27050402,XDB17000000)+2 种基金the Chinese Academy of Sciences Key Research Program of Frontier Sciences(QYZDY-SSW-SMC003)Youth Innovation Promotion Association of CAS(2020081),CAS Interdisciplinary Innovation Team(JCTD-2020-06)the Fundamental Research Funds for the Central Universities(2018XZZX001-13).
文摘Photosystem I(PSI)is a large protein supercomplex that catalyzes the light-dependent oxidation of plastocyanin(or cytochrome c6)and the reduction of ferredoxin.This catalytic reaction is realized by a transmembrane electron transfer chain consisting of primary electron donor(a special chlorophyll(Chl)pair)and electron acceptors A_(0),A_(1),and three Fe_(4)S_(4) clusters,F_(X),F_(A),and F_(B).Here we report the PSI structure from a Chl d-dominated cyanobacterium Acaryochloris marina at 3.3Åresolution obtained by single-particle cryo-electron microscopy.The A.marina PSI exists as a trimer with three identical monomers.Surprisingly,the structure reveals a unique composition of electron transfer chain in which the primary electron acceptor A_(0) is composed of two pheophytin a rather than Chl a found in any other well-known PSI structures.A novel subunit Psa27 is observed in the A.marina PSI structure.In addition,77 Chls,13α-carotenes,two phylloquinones,three Fe-S clusters,two phosphatidyl glycerols,and one monogalactosyl-diglyceride were identified in each PSI monomer.Our results provide a structural basis for deciphering the mechanism of photosynthesis in a PSI complex with Chl d as the dominating pigments and absorbing far-red light.
