Sterol-regulatory element binding proteins(SREBPs)are the key transcriptional regulators of lipid metabolism.The activation of SREBP requires translocation of the SREBP precursor from the endoplasmic reticulum to the ...Sterol-regulatory element binding proteins(SREBPs)are the key transcriptional regulators of lipid metabolism.The activation of SREBP requires translocation of the SREBP precursor from the endoplasmic reticulum to the Golgi,where it is sequentially cleaved by site-1 protease(S1P)and site-2 protease and releases a nuclear form to modulate gene expression.To search for new genes regulating cholesterol metabolism,we perform a genome-wide CRISPR/Cas9 knockout screen and find that partner of site-1 protease(POSH),encoded by C120RF49,is critically involved in the SREBP signaling.Ablation of POSH decreases the generation of nuclear SREBP and reduces the expression of SREBP target genes.POSH binds S1P,which is synthesized as an inactive protease(form A)and becomes fully mature via a two-step autocatalytic process involving forms B/B and C/C.POSH promotes the generation of the functional S1P-C/C from S1P-B/B(canonical cleavage)and,notably,from S1P-A directly(non-canonical cleavage)as well.This POSH-mediated S1P activation is also essential for the cleavages of other S1P substrates including ATF6,CREB3 family members and the a/p-subunit precursor of N-acetylglucosamine-1-phospho-transferase.Together,we demonstrate that POSH is a cofactor controlling S1P maturation and plays important roles in lipid homeostasis,unfolded protein response,lipoprotein metabolism and lysosome biogenesis.展开更多
Sunlight-driven activation of molecular oxygen(O_(2))for organic oxidation reactions offers an appealing strategy to cut down the reliance on fossil fuels in chemical industry,yet it remains a great challenge to simul...Sunlight-driven activation of molecular oxygen(O_(2))for organic oxidation reactions offers an appealing strategy to cut down the reliance on fossil fuels in chemical industry,yet it remains a great challenge to simultaneously tailor the charge kinetics and promote reactant chemisorption on semiconductor catalysts for enhanced photocatalytic performance.Herein,we report iron sites immobilized on defective BiOBr nanosheets as an efficient and selective photocatalyst for activation of O_(2) to singlet oxygen(^(1)O_(2)).These Fe^(3+) species anchored by oxygen vacancies can not only facilitate the separation and migration of photogenerated charge carrier,but also serve as active sites for effective adsorption of 02.Moreover,low-temperature phosphorescence spectra combined with X-ray photoelectron spectroscopy(XPS)and electronic paramagnetic resonance(EPR)spectra under illumination reveal that the Fe species can boost the quantum yield of excited triplet state and accelerate the energy transfer from excited triplet state to adsorbed O2 via a chemical loop of Fe^(3+)/Fe^(2+),thereby achieving highly efficient and selective generation of ^(1)O_(2).As a result,the versatile iron sites on defective BiOBr nanosheets contributes to near-unity conversion rate and selectivity in both aerobic oxidative coupling of amines to imines and sulfoxidation of organic sulfides.This work highlights the significant role of metal sites anchored on semiconductors in regulating the charge/energy transfer during the heterogeneous photocatalytic process,and provides a new angle for designing high-performance photocatalysts.展开更多
The activation and inactivation of adenylate kinase during denaturation in urea are compared with changes in UV absorbance at 287 nm, CD spectrum change at 222 nm, fluorescence intensity of ANS binding and small angle...The activation and inactivation of adenylate kinase during denaturation in urea are compared with changes in UV absorbance at 287 nm, CD spectrum change at 222 nm, fluorescence intensity of ANS binding and small angle of X ray scattering. At 1 mol/L of urea the enzyme is activated 1.5 fold companied with a subtle decreasing of its second structure, whereas its tertiary structure is fairly resistant to denaturation. By comparing the studies of the crystal structure and the mechanism of the catalysis of adenylate kinase, the activation is believed to result from the effect that low concentration of urea increases the flexibility of the active site of the enzyme. This suggestion was confirmed by the results of the fluorescence intensity changes of ANS binding to adenylate kinase versus the concentration of urea.展开更多
As a crucial signaling molecule, calcium plays a critical role in many physiological and pathological processes by regulating ion channel activity. Recently, one study resolved the structure of the transient receptor ...As a crucial signaling molecule, calcium plays a critical role in many physiological and pathological processes by regulating ion channel activity. Recently, one study resolved the structure of the transient receptor potential melastatin 2(TRPM2) channel from Nematostella vectensis(nvTRPM2). This identified a calcium-binding site in the S2–S3 loop, while its effect on channel gating remains unclear. Here, we investigated the role of this calcium-binding site in both nvTRPM2 and human TRPM2(hTRPM2) by mutagenesis and patch-clamp recording. Unlike hTRPM2, nvT RPM2 cannot be activated by calcium alone. Moreover, the inactivation rate of nvTRPM2 was decreased as intracellular calcium concentration was increased. In addition, our results showed that the four key residues in the calcium-binding site of S2–S3 loop have similar effects on the gating processes of nvTRPM2 and hTRPM2. Among them, the mutations at negatively charged residues(glutamate and aspartate) substantially decreased the currents of nvT RPM2 and hTRPM2. This suggests that these sites are essential for calcium-dependent channel gating. For the charge-neutralizing residues(glutamine and asparagine) in the calcium-binding site, our data showed that glutamine mutating to alanine or glutamate did not affect the channel activity, but glutamine mutating to lysine caused loss of function. Asparagine mutating to aspartate still remained functional, while asparagine mutating to alanine or lysine led to little channel activity. These results suggest that the side chain of glutamine has a less contribution to channel gating than does asparagine. However, our data indicated that both glutamine mutating to alanine or glutamate and asparagine mutating to aspartate accelerated the channel inactivation rate, suggesting that the calcium-binding site in the S2–S3 loop is important for calcium-dependent channel inactivation. Taken together, our results uncovered the effect of four key residues in the S2–S3 loop of TRPM2 on the TRPM2 gating process.展开更多
Identifying and engineering active sites play a key role in many catalytic reactions.Herein,we create well-defined surface structures through the growth of porous single-crystalline Mn_(3)O_(4) and Mn_(2)O_(3) monolit...Identifying and engineering active sites play a key role in many catalytic reactions.Herein,we create well-defined surface structures through the growth of porous single-crystalline Mn_(3)O_(4) and Mn_(2)O_(3) monoliths at centimeter scale and confine atomically dispersed Pt ions in the lattice at the twisted surface to construct isolated active sites.The activation of lattice oxygen linked to isolated Pt ions is much more effective than the lattice oxygen linked to Mn ions in local structures,leading to an approximately sevento eightfold enhancement of surface oxygen exchange coefficients for catalytic CO oxidation.The active structures of PtO_(1.5) and PtO_(1.4) confined at the well-defined surfaces contribute to the efficient activation of lattice oxygen linked to Pt ions in local structures in addition to the chemisorption of CO in the oxidation reaction.We demonstrate the complete CO oxidation with air at 65℃ without degradation being observed even after continuous operation of 300 h.展开更多
The relation between catalytic reactivities and metal/metal oxide ratios, as well as the functions of the metal and the metal oxides were investigated in the CO_2 hydrogenation reaction over highly active Co_x(CoO)_(1...The relation between catalytic reactivities and metal/metal oxide ratios, as well as the functions of the metal and the metal oxides were investigated in the CO_2 hydrogenation reaction over highly active Co_x(CoO)_(1–x)catalysts in operando. The catalytic reactivity of the samples in the CO_2 methanation improves with the increased Co O concentration. Strikingly, the sample with the highest concentration of CoO, i.e., Co_(0.2)(CoO)_(0.8), shows activity at temperatures lower than 200 °C where the other samples with less CoO are inactive. The origins of this improvement are the increased amount and moderate binding of adsorbed CO_2 on CoO sites. The derivative adsorption species are found to be intermediates of the CH4 formation. The metallic Co functions as the electronically catalytic site which provides electrons for the hydrogenation steps. As a result, an abundant amount of CoO combined with Co is the optimal composition of the catalyst for achieving the highest reactivity for CO_2 hydrogenation.展开更多
Diatomic-site catalysts(DASCs)have emerged as a kind of promising heterogeneous candidate catalysts for electrochemical CO_(2)reduction(ECR),which is considered to retain the advantage of single-atom catalysts(SACs)bu...Diatomic-site catalysts(DASCs)have emerged as a kind of promising heterogeneous candidate catalysts for electrochemical CO_(2)reduction(ECR),which is considered to retain the advantage of single-atom catalysts(SACs)but also introduce opportunities to exceed the limit of single-atom catalysts.In the past few years,tremendous progress has been achieved in this field.Herein,the recent progress in ECR on DASCs has been summarized.It will start with the classification of DASCs.Then the challenges in the precise fabrication and characterization of DASCs have been emphasized.By introducing the advanced ECR performance on DASCs,superior to that on SACs,the synergistic effects of the dual metal atoms are highlighted,as this origin of the advanced ECR performance on DASCs is comprehensively summarized.Finally,the major challenges and perspectives of DASCs have been proposed to shed light on the development of DASCs for ECR application.展开更多
文摘Sterol-regulatory element binding proteins(SREBPs)are the key transcriptional regulators of lipid metabolism.The activation of SREBP requires translocation of the SREBP precursor from the endoplasmic reticulum to the Golgi,where it is sequentially cleaved by site-1 protease(S1P)and site-2 protease and releases a nuclear form to modulate gene expression.To search for new genes regulating cholesterol metabolism,we perform a genome-wide CRISPR/Cas9 knockout screen and find that partner of site-1 protease(POSH),encoded by C120RF49,is critically involved in the SREBP signaling.Ablation of POSH decreases the generation of nuclear SREBP and reduces the expression of SREBP target genes.POSH binds S1P,which is synthesized as an inactive protease(form A)and becomes fully mature via a two-step autocatalytic process involving forms B/B and C/C.POSH promotes the generation of the functional S1P-C/C from S1P-B/B(canonical cleavage)and,notably,from S1P-A directly(non-canonical cleavage)as well.This POSH-mediated S1P activation is also essential for the cleavages of other S1P substrates including ATF6,CREB3 family members and the a/p-subunit precursor of N-acetylglucosamine-1-phospho-transferase.Together,we demonstrate that POSH is a cofactor controlling S1P maturation and plays important roles in lipid homeostasis,unfolded protein response,lipoprotein metabolism and lysosome biogenesis.
基金supported by the National Key R&D Program of China(No.2017YFA0700104)the National Natural Science Foundation of China(Nos.21905204,21931007,and 21790052)111 Project of China(No.D17003).
文摘Sunlight-driven activation of molecular oxygen(O_(2))for organic oxidation reactions offers an appealing strategy to cut down the reliance on fossil fuels in chemical industry,yet it remains a great challenge to simultaneously tailor the charge kinetics and promote reactant chemisorption on semiconductor catalysts for enhanced photocatalytic performance.Herein,we report iron sites immobilized on defective BiOBr nanosheets as an efficient and selective photocatalyst for activation of O_(2) to singlet oxygen(^(1)O_(2)).These Fe^(3+) species anchored by oxygen vacancies can not only facilitate the separation and migration of photogenerated charge carrier,but also serve as active sites for effective adsorption of 02.Moreover,low-temperature phosphorescence spectra combined with X-ray photoelectron spectroscopy(XPS)and electronic paramagnetic resonance(EPR)spectra under illumination reveal that the Fe species can boost the quantum yield of excited triplet state and accelerate the energy transfer from excited triplet state to adsorbed O2 via a chemical loop of Fe^(3+)/Fe^(2+),thereby achieving highly efficient and selective generation of ^(1)O_(2).As a result,the versatile iron sites on defective BiOBr nanosheets contributes to near-unity conversion rate and selectivity in both aerobic oxidative coupling of amines to imines and sulfoxidation of organic sulfides.This work highlights the significant role of metal sites anchored on semiconductors in regulating the charge/energy transfer during the heterogeneous photocatalytic process,and provides a new angle for designing high-performance photocatalysts.
文摘The activation and inactivation of adenylate kinase during denaturation in urea are compared with changes in UV absorbance at 287 nm, CD spectrum change at 222 nm, fluorescence intensity of ANS binding and small angle of X ray scattering. At 1 mol/L of urea the enzyme is activated 1.5 fold companied with a subtle decreasing of its second structure, whereas its tertiary structure is fairly resistant to denaturation. By comparing the studies of the crystal structure and the mechanism of the catalysis of adenylate kinase, the activation is believed to result from the effect that low concentration of urea increases the flexibility of the active site of the enzyme. This suggestion was confirmed by the results of the fluorescence intensity changes of ANS binding to adenylate kinase versus the concentration of urea.
基金Project supported by the National Natural Science Foundation oX f China(Nos.81371302,81571127,and 31872796)the National Basic Research Program(973)of China(No.2014CB910300)+1 种基金the National Major New Drugs Innovation and Development(No.2018ZX X09711001-004-005)the Zhejiang Provincial Natural Science Foundation of China(Nos.LR16H090001 and LY19B020013)
文摘As a crucial signaling molecule, calcium plays a critical role in many physiological and pathological processes by regulating ion channel activity. Recently, one study resolved the structure of the transient receptor potential melastatin 2(TRPM2) channel from Nematostella vectensis(nvTRPM2). This identified a calcium-binding site in the S2–S3 loop, while its effect on channel gating remains unclear. Here, we investigated the role of this calcium-binding site in both nvTRPM2 and human TRPM2(hTRPM2) by mutagenesis and patch-clamp recording. Unlike hTRPM2, nvT RPM2 cannot be activated by calcium alone. Moreover, the inactivation rate of nvTRPM2 was decreased as intracellular calcium concentration was increased. In addition, our results showed that the four key residues in the calcium-binding site of S2–S3 loop have similar effects on the gating processes of nvTRPM2 and hTRPM2. Among them, the mutations at negatively charged residues(glutamate and aspartate) substantially decreased the currents of nvT RPM2 and hTRPM2. This suggests that these sites are essential for calcium-dependent channel gating. For the charge-neutralizing residues(glutamine and asparagine) in the calcium-binding site, our data showed that glutamine mutating to alanine or glutamate did not affect the channel activity, but glutamine mutating to lysine caused loss of function. Asparagine mutating to aspartate still remained functional, while asparagine mutating to alanine or lysine led to little channel activity. These results suggest that the side chain of glutamine has a less contribution to channel gating than does asparagine. However, our data indicated that both glutamine mutating to alanine or glutamate and asparagine mutating to aspartate accelerated the channel inactivation rate, suggesting that the calcium-binding site in the S2–S3 loop is important for calcium-dependent channel inactivation. Taken together, our results uncovered the effect of four key residues in the S2–S3 loop of TRPM2 on the TRPM2 gating process.
基金supported by the National Key Research and Development Program of China(no.2017YFA0700102)Natural Science Foundation of China Foundation(no.91845202)Strategic Priority Research Program of Chinese Academy of Sciences(no.XDB2000000).
文摘Identifying and engineering active sites play a key role in many catalytic reactions.Herein,we create well-defined surface structures through the growth of porous single-crystalline Mn_(3)O_(4) and Mn_(2)O_(3) monoliths at centimeter scale and confine atomically dispersed Pt ions in the lattice at the twisted surface to construct isolated active sites.The activation of lattice oxygen linked to isolated Pt ions is much more effective than the lattice oxygen linked to Mn ions in local structures,leading to an approximately sevento eightfold enhancement of surface oxygen exchange coefficients for catalytic CO oxidation.The active structures of PtO_(1.5) and PtO_(1.4) confined at the well-defined surfaces contribute to the efficient activation of lattice oxygen linked to Pt ions in local structures in addition to the chemisorption of CO in the oxidation reaction.We demonstrate the complete CO oxidation with air at 65℃ without degradation being observed even after continuous operation of 300 h.
基金financially supported by Innosuisse, the Swiss Innovation Agency, is gratefully acknowledgedThe NAPXPS system is funded by the SNSF R’EQUIP project (No. 170736)+1 种基金the financial support from SNSF (Ambizione Project PZ00P2_179989)the China Scholarship Council for the PhD grant (Grant No. 201506060156)。
文摘The relation between catalytic reactivities and metal/metal oxide ratios, as well as the functions of the metal and the metal oxides were investigated in the CO_2 hydrogenation reaction over highly active Co_x(CoO)_(1–x)catalysts in operando. The catalytic reactivity of the samples in the CO_2 methanation improves with the increased Co O concentration. Strikingly, the sample with the highest concentration of CoO, i.e., Co_(0.2)(CoO)_(0.8), shows activity at temperatures lower than 200 °C where the other samples with less CoO are inactive. The origins of this improvement are the increased amount and moderate binding of adsorbed CO_2 on CoO sites. The derivative adsorption species are found to be intermediates of the CH4 formation. The metallic Co functions as the electronically catalytic site which provides electrons for the hydrogenation steps. As a result, an abundant amount of CoO combined with Co is the optimal composition of the catalyst for achieving the highest reactivity for CO_2 hydrogenation.
基金supported by“Pioneer”and“Leading Goose”R&D Program of Zhejiang(No.2023C03017)National Natural Science Foundation of China(Nos.22225606,22261142663,and 22176029)+1 种基金China Postdoctoral Science Foundation(No.2023M730491)Natural Science Foundation of Huzhou City(No.2022YZ22)。
文摘Diatomic-site catalysts(DASCs)have emerged as a kind of promising heterogeneous candidate catalysts for electrochemical CO_(2)reduction(ECR),which is considered to retain the advantage of single-atom catalysts(SACs)but also introduce opportunities to exceed the limit of single-atom catalysts.In the past few years,tremendous progress has been achieved in this field.Herein,the recent progress in ECR on DASCs has been summarized.It will start with the classification of DASCs.Then the challenges in the precise fabrication and characterization of DASCs have been emphasized.By introducing the advanced ECR performance on DASCs,superior to that on SACs,the synergistic effects of the dual metal atoms are highlighted,as this origin of the advanced ECR performance on DASCs is comprehensively summarized.Finally,the major challenges and perspectives of DASCs have been proposed to shed light on the development of DASCs for ECR application.
