Capsaicin in chili peppers bestows the sensation of spiciness. Since the discovery of its receptor, transient receptor potential vanilloid 1 （TRPV1） ion channel, how capsaicin activates this channel has been under e...Capsaicin in chili peppers bestows the sensation of spiciness. Since the discovery of its receptor, transient receptor potential vanilloid 1 （TRPV1） ion channel, how capsaicin activates this channel has been under extensive investigation using a variety of experimental techniques including mutagenesis, patch-clamp recording, crystallography, cryo-electron microscopy, computational docking and molecular dynamic simu- lation. A framework of how capsaicin binds and acti- vates TRPV1 has started to merge： capsaicin binds to a pocket formed by the channel＇s transmembrane seg- ments, where it takes a ＂tail-up, head-down＂ configu- ration. Binding is mediated by both hydrogen bonds and van der Waals interactions. Upon binding, cap- saicin stabilizes the open state of TRPV1 by ＂pull-and- contact＂ with the $4-$5 linker. Understanding the ligand-host interaction will greatly facilitate pharma- ceutical efforts to develop novel analgesics targeting TRPV1.展开更多
As we know more about Zika virus(ZIKV), as well as its linkage to birth defects(microcephaly) and autoimmune neurological syndromes, we realize the importance of developing an efficient vaccine against it. Zika virus ...As we know more about Zika virus(ZIKV), as well as its linkage to birth defects(microcephaly) and autoimmune neurological syndromes, we realize the importance of developing an efficient vaccine against it. Zika virus disease has affected many countries and is becoming a major public health concern. To deal with the infection of ZIKV, plenty of experiments have been done on selection of neutralizing antibodies that can target the envelope(E) protein on the surface of the virion. However, the existence of antibody-dependent enhancement(ADE) effect might limit the use of them as therapeutic candidates. In this review, we classify the neutralizing antibodies against ZIKV based on the epitopes and summarize the resolved structural information on antibody/antigen complex from X-ray crystallography and cryo-electron microscopy(cryo-EM), which might be useful for further development of potent neutralizing antibodies and vaccines toward clinical use.展开更多
Cellular hormone homeostasis is essential for precise spatial and temporal signaling responses and plantfitness.Abscisic acid(ABA)plays pivotal roles in orchestrating various developmental and stress re-sponses and co...Cellular hormone homeostasis is essential for precise spatial and temporal signaling responses and plantfitness.Abscisic acid(ABA)plays pivotal roles in orchestrating various developmental and stress re-sponses and confersfitness benefits over ecological and evolutionary timescales in terrestrial plants.Cellular ABA level is regulated by complex processes,including biosynthesis,catabolism,and transport.AtABCG25 is thefirst ABA exporter identified through genetic screening and affects diverse ABA responses.Resolving the structural basis of ABA export by ABCG25 is critical for further manipulations of ABA homeostasis and plantfitness.We used cryo-electron microscopy to elucidate the structural dynamics of AtABCG25 and successfully characterized different states,including apo AtABCG25,ABA-bound AtABCG25,and ATP-bound AtABCG25(E232Q).Notably,AtABCG25 forms a homodimer that fea-tures a deep,slit-like cavity in the transmembrane domain,and we precisely characterized the critical residues in the cavity where ABA binds.ATP binding triggers closure of the nucleotide-binding domains and conformational transitions in the transmembrane domains.We show that AtABCG25 belongs to a conserved ABCG subfamily that originated during the evolution of angiosperms.This subfamily neofunctionalized to regulate seed germination via the endosperm,in concert with the evolution of this angio-sperm-specific,embryo-nourishing tissue.Collectively,thesefindings provide valuable insights into the intricate substrate recognition and transport mechanisms of the ABA exporter AtABCG25,paving the way for genetic manipulation of ABA homeostasis and plantfitness.展开更多
γ-Secretase,called“the proteasome of the membrane,”is a membrane-embedded protease complex that cleaves 150+peptide substrates with central roles in biology and medicine,including amyloid precursor protein and the ...γ-Secretase,called“the proteasome of the membrane,”is a membrane-embedded protease complex that cleaves 150+peptide substrates with central roles in biology and medicine,including amyloid precursor protein and the Notch family of cell-surface receptors.Mutations inγ-secretase and amyloid precursor protein lead to early-onset familial Alzheimer’s disease.γ-Secretase has thus served as a critical drug target for treating familial Alzheimer’s disease and the more common late-onset Alzheimer’s disease as well.However,critical gaps remain in understanding the mechanisms of processive proteolysis of substrates,the effects of familial Alzheimer’s disease mutations,and allosteric modulation of substrate cleavage byγ-secretase.In this review,we focus on recent studies of structural dynamic mechanisms ofγ-secretase.Different mechanisms,including the“Fit-Stay-Trim,”“Sliding-Unwinding,”and“Tilting-Unwinding,”have been proposed for substrate proteolysis of amyloid precursor protein byγ-secretase based on all-atom molecular dynamics simulations.While an incorrect registry of the Notch1 substrate was identified in the cryo-electron microscopy structure of Notch1-boundγ-secretase,molecular dynamics simulations on a resolved model of Notch1-boundγ-secretase that was reconstructed using the amyloid precursor protein-boundγ-secretase as a template successfully capturedγ-secretase activation for proper cleavages of both wildtype and mutant Notch,being consistent with biochemical experimental findings.The approach could be potentially applied to decipher the processing mechanisms of various substrates byγ-secretase.In addition,controversy over the effects of familial Alzheimer’s disease mutations,particularly the issue of whether they stabilize or destabilizeγ-secretase-substrate complexes,is discussed.Finally,an outlook is provided for future studies ofγ-secretase,including pathways of substrate binding and product release,effects of modulators on familial Alzheimer’s disease mutations of the展开更多
近年来,科学家应用冷冻电镜技术（cryo-EM）解析出了低对称性生物大分子的高分辨率（3~5魡）三维结构,并用其密度图直接进行了分子建模。与传统的X-射线和NMR方法相比,冷冻电镜技术具有适用于分子量较大的生物分子、样品不需结晶且用量...近年来,科学家应用冷冻电镜技术（cryo-EM）解析出了低对称性生物大分子的高分辨率（3~5魡）三维结构,并用其密度图直接进行了分子建模。与传统的X-射线和NMR方法相比,冷冻电镜技术具有适用于分子量较大的生物分子、样品不需结晶且用量很少等优势。尤其是电子直接探测相机（electron direct detection device,DDD）在冷冻电镜技术中的应用,使高分辨率的结构研究变得更加简单、应用更为广泛,是一个重大突破。文章介绍DDD相机的原理和技术优势,及其在解决冷冻电镜技术困难中的一些应用,进而展望了DDD相机可能给冷冻电镜技术应用带来的突破性进展。展开更多
The outbreak of severe acute respiratory syndrome coronavirus 2(SARSCoV-2)has developed into an unprecedented global pandemic.Nucleoside analogs,such as Remdesivir and Favipiravir,can serve as the firstline broad-spec...The outbreak of severe acute respiratory syndrome coronavirus 2(SARSCoV-2)has developed into an unprecedented global pandemic.Nucleoside analogs,such as Remdesivir and Favipiravir,can serve as the firstline broad-spectrum antiviral drugs by targeting the viral polymerases.However,the underlying mechanisms for the antiviral efficacies of these drugs are far from well understood.Here,we reveal that Favipiravir,as a pyrazine derivative,could be incorporated into the viral RNA products by mimicking both adenine and guanine nucleotides.This drug thus inhibits viral replication mainly by inducing mutations in progeny RNAs,different from Remdesivir or other RNA-terminating nucleoside analogs that impair the elongation of RNA products.We further determined the cryo-EM structure of Favipiravir bound to the replicating polymerase complex of SARSCoV-2 in the pre-catalytic state.This structure provides a missing snapshot for visualizing the catalysis dynamics of coronavirus polymerase,and reveals an unexpected base-pairing pattern between Favipiravir and pyrimidine residues that may explain its capacity for mimicking both adenine and guanine nucleotides.These findings shed light on the mechanism of coronavirus polymerase catalysis and provide a rational basis for developing antiviral drugs to combat the SARS-CoV-2 pandemic.展开更多
Intracellular compartmentation is a key strategy for the functioning of a cell.In 2010,several studies revealed that the metabolic enzyme CTP synthase(CTPS)can form filamentous structures termed cytoophidia in prokary...Intracellular compartmentation is a key strategy for the functioning of a cell.In 2010,several studies revealed that the metabolic enzyme CTP synthase(CTPS)can form filamentous structures termed cytoophidia in prokaryotic and eukaryotic cells.However,recent structural studies showed that CTPS only forms inactive product-bound filaments in bacteria while forming active substrate-bound filaments in eukaryotic cells.In this study,using negative staining and cryo-electron microscopy,we demonstrate that Drosophila CTPS,whether in substrate-bound or product-bound form,can form filaments.Our results challenge the previous model and indicate that substrate-bound and product-bound filaments can coexist in the same species.We speculate that the ability to switch between active and inactive cytoophidia in the same cells provides an additional layer of metabolic regulation.展开更多
Mechanosensitive channels mediate touch,hearing,proprioception,and blood pressure regulation.Piezo proteins,including Piezo1 and Piezo2,represent a new class of mechanosensitive channels that have been reported to pla...Mechanosensitive channels mediate touch,hearing,proprioception,and blood pressure regulation.Piezo proteins,including Piezo1 and Piezo2,represent a new class of mechanosensitive channels that have been reported to play key roles in most,if not all,of these modalities.The structural architecture and molecular mechanisms by which Piezos act as mechanosensitive channels,however,remain mysterious.Two new studies have now provided critical insights into the atomic structure and molecular basis of the ion permeation and mechano-gating properties of the Piezo1 channel.展开更多
The human Shwachman-Diamond syndrome （SDS） is an autosomal recessive disease caused by mutations in a highly conserved ribosome assembly factor SBDS. The functional role of SBDS is to cooperate with another assembly...The human Shwachman-Diamond syndrome （SDS） is an autosomal recessive disease caused by mutations in a highly conserved ribosome assembly factor SBDS. The functional role of SBDS is to cooperate with another assembly factor, elongation factor l-like （Eft1）, to pro- mote the release of eukaryotic initiation factor 6 （elF6） from the late-stage cytoplasmic 60S precursors. In the present work, we characterized, both biochemically and structurally, the interaction between the 60S subunit and SBDS protein （Sdolp） from yeast. Our data show that Sdolp interacts tightly with the mature 60S subunit in vitro through its domain I and II, and is capable of bridging two 60S subunits to form a stable 2：2 dimer. Structural analysis indicates that Sdolp bind to the ribosomal P-site, in the proximity of uL16 and uL5, and with direct contact to H69 and H38. The dynamic nature of Sdolp on the 60S subunit, together with its strategic binding position, suggests a surveillance role of Sdolp in monitoring the conformational maturation of the ribosomal P-site. Altogether, our data support a con- formational signal-relay cascade during late-stage 60S maturation, involving uL16, Sdolp, and Efllp, which interrogates the functional P-site to control the departure of the anti-association factor elF6.展开更多
Recent technical breakthroughs in cryo-electron microscopy（cryo-EM） revolutionized structural biology, which led to the 2017 Nobel Prize in chemistry being awarded to three scientists, Jacques Dubochet, Joachim Fran...Recent technical breakthroughs in cryo-electron microscopy（cryo-EM） revolutionized structural biology, which led to the 2017 Nobel Prize in chemistry being awarded to three scientists, Jacques Dubochet, Joachim Frank, and Richard Henderson, who made groundbreaking contributions to the development of cryo-EM. In this review, I will give a comprehensive review of the developmental history of cryo-EM, the technical aspects of the breakthrough in cryo-EM leading to the structural biology revolution, including electron microscopy, image recording devices and image processing algorithms,and the major scientific achievements by Chinese researchers employing cryo-EM, covering protein complexes involved in or related to gene expression and regulation, protein synthesis and degradation, membrane proteins, immunity, and viruses.Finally, I will give a perspective outlook on the development of cryo-EM in the future.展开更多
Reconstituting membrane proteins in liposomes and determining their structure is a common method for determining membrane protein structures using single-particle cryo-electron microscopy(cryo-EM).However,the strong s...Reconstituting membrane proteins in liposomes and determining their structure is a common method for determining membrane protein structures using single-particle cryo-electron microscopy(cryo-EM).However,the strong signal of liposomes under cryo-EM imaging conditions often interferes with the structural determination of the embedded membrane proteins.Here,we propose a liposome signal subtraction method based on single-particle two-dimensional(2D)classification average images,aimed at enhancing the reconstruction resolution of membrane proteins.We analyzed the signal distribution characteristics of liposomes and proteins within the 2D classification average images of protein–liposome complexes in the frequency domain.Based on this analysis,we designed a method to subtract the liposome signals from the original particle images.After the subtraction,the accuracy of single-particle three-dimensional(3D)alignment was improved,enhancing the resolution of the final 3D reconstruction.We demonstrated this method using a PIEZO1-proteoliposome dataset by improving the resolution of the PIEZO1 protein.展开更多
Silk is one of the toughest fibrous materials known despite spun at ambient temperature and pressure with water as a solvent.It is a great challenge to reproduce high-performance artificial fibers comparable to natura...Silk is one of the toughest fibrous materials known despite spun at ambient temperature and pressure with water as a solvent.It is a great challenge to reproduce high-performance artificial fibers comparable to natural silk by bionic for the incomplete understanding of silkworm spinning in vivo.Here,we found that amphipol and digitonin stabilized the structure of natural silk fibroin(NSF)by a large-scale screening in vitro,and then studied the close-to-native ultrastructure and hierarchical assembly of NSF in the silk gland lumen.Our study showed that NSF formed reversible flexible nanofibrils mainly composed of random coils with a sedimentation coefficient of 5.8 S and a diameter of about 4 nm,rather than a micellar or rod-like structure assembled by the aggregation of globular NSF molecules.Metal ions were required for NSF nanofibril formation.The successive p H decrease from posterior silk gland(PSG)to anterior silk gland(ASG)resulted in a gradual increase in NSF hydrophobicity,thus inducing the sol-gelation transition of NSF nanofibrils.NSF nanofibrils were randomly dispersed from PSG to ASG-1,and self-assembled into anisotropic herringbone patterns at ASG-2 near the spinneret ready for silkworm spinning.Our findings reveal the controlled self-assembly mechanism of the multi-scale hierarchical architecture of NSF from nanofibrils to herringbone patterns programmed by metal ions and p H gradient,which provides novel insights into the spinning mechanism of silk-secreting animals and bioinspired design of high-performance fibers.展开更多
Thousands of nuclear-encoded proteins are transported into chloroplasts through the TOC–TIC translocon that spans the chloroplast envelope membranes.A motor complex pulls the translocated proteins out of the TOC–TIC...Thousands of nuclear-encoded proteins are transported into chloroplasts through the TOC–TIC translocon that spans the chloroplast envelope membranes.A motor complex pulls the translocated proteins out of the TOC–TIC complex into the chloroplast stroma by hydrolyzing ATP.The Orf2971–FtsHi complex has been suggested to serve as the ATP-hydrolyzing motor in Chlamydomonas reinhardtii,but little is known about its architecture and assembly.Here,we report the 3.2-Åresolution structure of the Chlamydomonas Orf2971–FtsHi complex.The 20-subunit complex spans the chloroplast inner envelope,with two bulky modules protruding into the intermembrane space and stromal matrix.Six subunits form a hetero-hexamer that potentially provides the pulling force through ATP hydrolysis.The remaining subunits,including potential enzymes/chaperones,likely facilitate the complex assembly and regulate its proper function.Taken together,our results provide the structural foundation for a mechanistic understanding of chloroplast protein translocation.展开更多
文摘Capsaicin in chili peppers bestows the sensation of spiciness. Since the discovery of its receptor, transient receptor potential vanilloid 1 （TRPV1） ion channel, how capsaicin activates this channel has been under extensive investigation using a variety of experimental techniques including mutagenesis, patch-clamp recording, crystallography, cryo-electron microscopy, computational docking and molecular dynamic simu- lation. A framework of how capsaicin binds and acti- vates TRPV1 has started to merge： capsaicin binds to a pocket formed by the channel＇s transmembrane seg- ments, where it takes a ＂tail-up, head-down＂ configu- ration. Binding is mediated by both hydrogen bonds and van der Waals interactions. Upon binding, cap- saicin stabilizes the open state of TRPV1 by ＂pull-and- contact＂ with the $4-$5 linker. Understanding the ligand-host interaction will greatly facilitate pharma- ceutical efforts to develop novel analgesics targeting TRPV1.
基金funded by the External Cooperation Program of Chinese Academy of Sciences (Grant No. 153211KYSB20160001)the National Key Research and Development Program of China (Grant No. 2016YFC1202902)+1 种基金the Key Program of Chinese Academy of Sciences (Grant No. ZDRW-ZS2016-4)funded by FNLCR Contract HHSN261200800001E
文摘As we know more about Zika virus(ZIKV), as well as its linkage to birth defects(microcephaly) and autoimmune neurological syndromes, we realize the importance of developing an efficient vaccine against it. Zika virus disease has affected many countries and is becoming a major public health concern. To deal with the infection of ZIKV, plenty of experiments have been done on selection of neutralizing antibodies that can target the envelope(E) protein on the surface of the virion. However, the existence of antibody-dependent enhancement(ADE) effect might limit the use of them as therapeutic candidates. In this review, we classify the neutralizing antibodies against ZIKV based on the epitopes and summarize the resolved structural information on antibody/antigen complex from X-ray crystallography and cryo-electron microscopy(cryo-EM), which might be useful for further development of potent neutralizing antibodies and vaccines toward clinical use.
基金supported by the National Natural Science Foundation of China (grant 32271251 to K.Y.,grant 32070292 to J.L.)the Guangdong Innovative and Entrepreneurial Research Team Program (grants 2021Z T09Y104 and 2021QN02Y429 to K.Y.)+2 种基金the Shenzhen Science and Technology Program (grants JCYJ20220530115214033 and KQTD20210811090115021 to K.Y.,grants JCYJ20170817104523456 and KQTD20190929173906742 to J.L.)Scientific research funding for postdoctoral researchers staying at Shenzhen (grant K20227507 to Y.Z.)supported by the Stable Support Plan Program of the Shenzhen Natural Science Fund (grant 20220815160107001).
文摘Cellular hormone homeostasis is essential for precise spatial and temporal signaling responses and plantfitness.Abscisic acid(ABA)plays pivotal roles in orchestrating various developmental and stress re-sponses and confersfitness benefits over ecological and evolutionary timescales in terrestrial plants.Cellular ABA level is regulated by complex processes,including biosynthesis,catabolism,and transport.AtABCG25 is thefirst ABA exporter identified through genetic screening and affects diverse ABA responses.Resolving the structural basis of ABA export by ABCG25 is critical for further manipulations of ABA homeostasis and plantfitness.We used cryo-electron microscopy to elucidate the structural dynamics of AtABCG25 and successfully characterized different states,including apo AtABCG25,ABA-bound AtABCG25,and ATP-bound AtABCG25(E232Q).Notably,AtABCG25 forms a homodimer that fea-tures a deep,slit-like cavity in the transmembrane domain,and we precisely characterized the critical residues in the cavity where ABA binds.ATP binding triggers closure of the nucleotide-binding domains and conformational transitions in the transmembrane domains.We show that AtABCG25 belongs to a conserved ABCG subfamily that originated during the evolution of angiosperms.This subfamily neofunctionalized to regulate seed germination via the endosperm,in concert with the evolution of this angio-sperm-specific,embryo-nourishing tissue.Collectively,thesefindings provide valuable insights into the intricate substrate recognition and transport mechanisms of the ABA exporter AtABCG25,paving the way for genetic manipulation of ABA homeostasis and plantfitness.
基金supported in part by Award 2121063 from National Science Foundation(to YM)AG66986 from the National Institutes of Health(to MSW).
文摘γ-Secretase,called“the proteasome of the membrane,”is a membrane-embedded protease complex that cleaves 150+peptide substrates with central roles in biology and medicine,including amyloid precursor protein and the Notch family of cell-surface receptors.Mutations inγ-secretase and amyloid precursor protein lead to early-onset familial Alzheimer’s disease.γ-Secretase has thus served as a critical drug target for treating familial Alzheimer’s disease and the more common late-onset Alzheimer’s disease as well.However,critical gaps remain in understanding the mechanisms of processive proteolysis of substrates,the effects of familial Alzheimer’s disease mutations,and allosteric modulation of substrate cleavage byγ-secretase.In this review,we focus on recent studies of structural dynamic mechanisms ofγ-secretase.Different mechanisms,including the“Fit-Stay-Trim,”“Sliding-Unwinding,”and“Tilting-Unwinding,”have been proposed for substrate proteolysis of amyloid precursor protein byγ-secretase based on all-atom molecular dynamics simulations.While an incorrect registry of the Notch1 substrate was identified in the cryo-electron microscopy structure of Notch1-boundγ-secretase,molecular dynamics simulations on a resolved model of Notch1-boundγ-secretase that was reconstructed using the amyloid precursor protein-boundγ-secretase as a template successfully capturedγ-secretase activation for proper cleavages of both wildtype and mutant Notch,being consistent with biochemical experimental findings.The approach could be potentially applied to decipher the processing mechanisms of various substrates byγ-secretase.In addition,controversy over the effects of familial Alzheimer’s disease mutations,particularly the issue of whether they stabilize or destabilizeγ-secretase-substrate complexes,is discussed.Finally,an outlook is provided for future studies ofγ-secretase,including pathways of substrate binding and product release,effects of modulators on familial Alzheimer’s disease mutations of the
文摘近年来,科学家应用冷冻电镜技术（cryo-EM）解析出了低对称性生物大分子的高分辨率（3~5魡）三维结构,并用其密度图直接进行了分子建模。与传统的X-射线和NMR方法相比,冷冻电镜技术具有适用于分子量较大的生物分子、样品不需结晶且用量很少等优势。尤其是电子直接探测相机（electron direct detection device,DDD）在冷冻电镜技术中的应用,使高分辨率的结构研究变得更加简单、应用更为广泛,是一个重大突破。文章介绍DDD相机的原理和技术优势,及其在解决冷冻电镜技术困难中的一些应用,进而展望了DDD相机可能给冷冻电镜技术应用带来的突破性进展。
基金We thank all staff members in the Center of Biological Imaging(CBI),the Institute of Biophysics(IBP),and the Chinese Academy of Sciences(CAS)for assistance with data collection.This study was supported by the Strategic Priority Research Program of CAS(XDB29010000)the National Science and Technology Major Project(2018ZX10101004)+3 种基金the National Key Research and Development Program of China(2020YFC0845900)the National Natural Science Foundation of China(NSFC)(82041016,81871658,and 81802010)a grant from the Bill&Melinda Gates Foundation,and is partially supported by the Yanqi Lake Meeting organized by the Academic Divisions of CAS.M.W.is supported by the National Science and Technology Major Project(2018ZX09711003)the National Natural Science Foundation of China(NSFC)(81802007).R.P.is supported by the Young Elite Scientist Sponsorship Program(YESS)by the China Association for Science and Technology(CAST)(2018QNRC001).Y.S.is also supported by the Youth Innovation Promotion Association of CAS.
文摘The outbreak of severe acute respiratory syndrome coronavirus 2(SARSCoV-2)has developed into an unprecedented global pandemic.Nucleoside analogs,such as Remdesivir and Favipiravir,can serve as the firstline broad-spectrum antiviral drugs by targeting the viral polymerases.However,the underlying mechanisms for the antiviral efficacies of these drugs are far from well understood.Here,we reveal that Favipiravir,as a pyrazine derivative,could be incorporated into the viral RNA products by mimicking both adenine and guanine nucleotides.This drug thus inhibits viral replication mainly by inducing mutations in progeny RNAs,different from Remdesivir or other RNA-terminating nucleoside analogs that impair the elongation of RNA products.We further determined the cryo-EM structure of Favipiravir bound to the replicating polymerase complex of SARSCoV-2 in the pre-catalytic state.This structure provides a missing snapshot for visualizing the catalysis dynamics of coronavirus polymerase,and reveals an unexpected base-pairing pattern between Favipiravir and pyrimidine residues that may explain its capacity for mimicking both adenine and guanine nucleotides.These findings shed light on the mechanism of coronavirus polymerase catalysis and provide a rational basis for developing antiviral drugs to combat the SARS-CoV-2 pandemic.
基金supported by grants from the National Natural Science Foundation of China(No.31771490)to J.-L.L.
文摘Intracellular compartmentation is a key strategy for the functioning of a cell.In 2010,several studies revealed that the metabolic enzyme CTP synthase(CTPS)can form filamentous structures termed cytoophidia in prokaryotic and eukaryotic cells.However,recent structural studies showed that CTPS only forms inactive product-bound filaments in bacteria while forming active substrate-bound filaments in eukaryotic cells.In this study,using negative staining and cryo-electron microscopy,we demonstrate that Drosophila CTPS,whether in substrate-bound or product-bound form,can form filaments.Our results challenge the previous model and indicate that substrate-bound and product-bound filaments can coexist in the same species.We speculate that the ability to switch between active and inactive cytoophidia in the same cells provides an additional layer of metabolic regulation.
文摘Mechanosensitive channels mediate touch,hearing,proprioception,and blood pressure regulation.Piezo proteins,including Piezo1 and Piezo2,represent a new class of mechanosensitive channels that have been reported to play key roles in most,if not all,of these modalities.The structural architecture and molecular mechanisms by which Piezos act as mechanosensitive channels,however,remain mysterious.Two new studies have now provided critical insights into the atomic structure and molecular basis of the ion permeation and mechano-gating properties of the Piezo1 channel.
文摘The human Shwachman-Diamond syndrome （SDS） is an autosomal recessive disease caused by mutations in a highly conserved ribosome assembly factor SBDS. The functional role of SBDS is to cooperate with another assembly factor, elongation factor l-like （Eft1）, to pro- mote the release of eukaryotic initiation factor 6 （elF6） from the late-stage cytoplasmic 60S precursors. In the present work, we characterized, both biochemically and structurally, the interaction between the 60S subunit and SBDS protein （Sdolp） from yeast. Our data show that Sdolp interacts tightly with the mature 60S subunit in vitro through its domain I and II, and is capable of bridging two 60S subunits to form a stable 2：2 dimer. Structural analysis indicates that Sdolp bind to the ribosomal P-site, in the proximity of uL16 and uL5, and with direct contact to H69 and H38. The dynamic nature of Sdolp on the 60S subunit, together with its strategic binding position, suggests a surveillance role of Sdolp in monitoring the conformational maturation of the ribosomal P-site. Altogether, our data support a con- formational signal-relay cascade during late-stage 60S maturation, involving uL16, Sdolp, and Efllp, which interrogates the functional P-site to control the departure of the anti-association factor elF6.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0504700)the National Natural Science Foundation of China(Grant Nos.31570732 and 31770785)
文摘Recent technical breakthroughs in cryo-electron microscopy（cryo-EM） revolutionized structural biology, which led to the 2017 Nobel Prize in chemistry being awarded to three scientists, Jacques Dubochet, Joachim Frank, and Richard Henderson, who made groundbreaking contributions to the development of cryo-EM. In this review, I will give a comprehensive review of the developmental history of cryo-EM, the technical aspects of the breakthrough in cryo-EM leading to the structural biology revolution, including electron microscopy, image recording devices and image processing algorithms,and the major scientific achievements by Chinese researchers employing cryo-EM, covering protein complexes involved in or related to gene expression and regulation, protein synthesis and degradation, membrane proteins, immunity, and viruses.Finally, I will give a perspective outlook on the development of cryo-EM in the future.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.32241023 and 92254306)the Fund from the Tsinghua–Peking Joint Center for Life SciencesBeijing Frontier Research Center for Biological Structure。
文摘Reconstituting membrane proteins in liposomes and determining their structure is a common method for determining membrane protein structures using single-particle cryo-electron microscopy(cryo-EM).However,the strong signal of liposomes under cryo-EM imaging conditions often interferes with the structural determination of the embedded membrane proteins.Here,we propose a liposome signal subtraction method based on single-particle two-dimensional(2D)classification average images,aimed at enhancing the reconstruction resolution of membrane proteins.We analyzed the signal distribution characteristics of liposomes and proteins within the 2D classification average images of protein–liposome complexes in the frequency domain.Based on this analysis,we designed a method to subtract the liposome signals from the original particle images.After the subtraction,the accuracy of single-particle three-dimensional(3D)alignment was improved,enhancing the resolution of the final 3D reconstruction.We demonstrated this method using a PIEZO1-proteoliposome dataset by improving the resolution of the PIEZO1 protein.
基金supported by the National Key Research and Development Program of China(2022YFD1201600,2021YFA1300100,and 2018YFE0203300)the National Natural Science Foundation of China(31972622 and 32241029)+6 种基金the State Key Program of National Natural Science Foundation of China(32030103)the Natural Science Foundation of Chongqing,China(CSTB2022NSCQ-LZX0302,CSTB2022NSCQ-MSX0761,and cstc2020jcyj-cxtt X0001)the Fundamental Research Funds for the Central Universities(XDJK2020TJ001)the Key Project of Science and Technology Research Program of Chongqing Municipal Education Commission,China(KJZD-K202200205)the Chinese Academy of Sciences(CAS)Strategic Priority Research Program(XDB37010100)the Shennong Youth Talent Program(Ministry of Agriculture and Rural Affairs,China)the Chongqing Innovation Supporting Program for Oversea Returned Talents(CX2023069)。
文摘Silk is one of the toughest fibrous materials known despite spun at ambient temperature and pressure with water as a solvent.It is a great challenge to reproduce high-performance artificial fibers comparable to natural silk by bionic for the incomplete understanding of silkworm spinning in vivo.Here,we found that amphipol and digitonin stabilized the structure of natural silk fibroin(NSF)by a large-scale screening in vitro,and then studied the close-to-native ultrastructure and hierarchical assembly of NSF in the silk gland lumen.Our study showed that NSF formed reversible flexible nanofibrils mainly composed of random coils with a sedimentation coefficient of 5.8 S and a diameter of about 4 nm,rather than a micellar or rod-like structure assembled by the aggregation of globular NSF molecules.Metal ions were required for NSF nanofibril formation.The successive p H decrease from posterior silk gland(PSG)to anterior silk gland(ASG)resulted in a gradual increase in NSF hydrophobicity,thus inducing the sol-gelation transition of NSF nanofibrils.NSF nanofibrils were randomly dispersed from PSG to ASG-1,and self-assembled into anisotropic herringbone patterns at ASG-2 near the spinneret ready for silkworm spinning.Our findings reveal the controlled self-assembly mechanism of the multi-scale hierarchical architecture of NSF from nanofibrils to herringbone patterns programmed by metal ions and p H gradient,which provides novel insights into the spinning mechanism of silk-secreting animals and bioinspired design of high-performance fibers.
基金funded by the Strategic Priority Research Program of CAS(XDB37020101)the National Key R&D Program of China(2021YFA0910800)+3 种基金the National Natural Science Foundation of China(31930064)the Youth Innovation Promotion Association,Chinese Academy of Sciences(Y2022038)the Regional Joint Key Projects of the National Foundation of China(U22A20445)the Natural Science Foundation of Shandong Province(ZR2023ZD30).
文摘Thousands of nuclear-encoded proteins are transported into chloroplasts through the TOC–TIC translocon that spans the chloroplast envelope membranes.A motor complex pulls the translocated proteins out of the TOC–TIC complex into the chloroplast stroma by hydrolyzing ATP.The Orf2971–FtsHi complex has been suggested to serve as the ATP-hydrolyzing motor in Chlamydomonas reinhardtii,but little is known about its architecture and assembly.Here,we report the 3.2-Åresolution structure of the Chlamydomonas Orf2971–FtsHi complex.The 20-subunit complex spans the chloroplast inner envelope,with two bulky modules protruding into the intermembrane space and stromal matrix.Six subunits form a hetero-hexamer that potentially provides the pulling force through ATP hydrolysis.The remaining subunits,including potential enzymes/chaperones,likely facilitate the complex assembly and regulate its proper function.Taken together,our results provide the structural foundation for a mechanistic understanding of chloroplast protein translocation.
