Present work was undertaken to screen some drought tolerant indigenous aromatic rice cultivars(IARCs),commonly cultivated in West Bengal,India,based on their capacity to produce osmolytes,redox-sensitive phenolic acid...Present work was undertaken to screen some drought tolerant indigenous aromatic rice cultivars(IARCs),commonly cultivated in West Bengal,India,based on their capacity to produce osmolytes,redox-sensitive phenolic acids and flavonoids,as contrivances for redox-regulation under drought stress.Polyethylene glycol induced post imbibitional dehydration stress mediated changes in redox regulatory properties of the germinating seeds of the four IARCs(Jamainadu,Tulaipanji,Sitabhog,Badshabhog),which were assessed in terms of changes in prooxidant accumulation(in-situ localization of reactive oxygen species(ROS)by confocal microscopy,DCFDA(2′,7′-dichlorofluorescin diacetate)oxidation,O2-and H2O2 accumulation),cumulative antioxidative defense(radical scavenging property and total thiol content),ROS scavenging phenolic acids(gallic acid,protocatechuic acid,gentisic acid,para-hydroxy benzoic acid,chlorogenic acid,caffeic acid,syringic acid,salicylic acid,sinapic acid and p-coumaric acid)and flavonoids(catechin,naringin,rutin,quercetin,kaempferol,myricetin and apigenin).The capability of germinating seeds to accumulate osmolytes(like glycinebetaine,proline,soluble carbohydrates and K+ion)and polyphenolic compounds was also correlated with their corresponding redox status and redox biomarkers(conjugated diene,hydroperoxide,thiobarbituric acid reactive substances and free carbonyl content)produced under the same conditions.The results in general showed that accumulation of osmolytes along with the redox-sensitive phenolics and flavonoids conferred the ability to maintain the redox homeostasis under drought stress for the tolerant IARCs(Badshabhog and Tulaipanji).展开更多
The durability of three-way catalyst （TWC） and corresponding close-coupled catalyst （CCC） for Euro Ⅳ stage regulation was investigated through Vehicle Road Running Mode tests, whereas emissions of regulated pollu...The durability of three-way catalyst （TWC） and corresponding close-coupled catalyst （CCC） for Euro Ⅳ stage regulation was investigated through Vehicle Road Running Mode tests, whereas emissions of regulated pollutants of three car fleet were investigated at every 100,000 km miles. The results showed that HC, NOx, and CO emission values could meet Euro Ⅳ regulation limits at every point. The redox properties of TWC and CCC were measured by CO reduction during each isothermal. It was obvious that both aged TWC and aged CCC behaved a good redox property at 673 and 773 K. Based on XRD and BET measurement results, TWC and CCC washcoat were characterized with good thermal stability.展开更多
MicroRNAs(miRs)are small regulatory RNA transcripts capable of post-transcriptional silencing of mRNA messages by entering a cellular bimolecular apparatus called RNA-induced silencing complex.miRs are involved in the...MicroRNAs(miRs)are small regulatory RNA transcripts capable of post-transcriptional silencing of mRNA messages by entering a cellular bimolecular apparatus called RNA-induced silencing complex.miRs are involved in the regulation of cellular processes producing,eliminating or repairing the damage caused by reactive oxygen species,and they are active players in redox homeostasis.Increased mitochondrial biogenesis,function and hypertrophy of skeletal muscle are important adaptive responses to regular exercise.In the present review,we highlight some of the redox-sensitive regulatory roles of miRs.展开更多
The stress-associated protein SAP12 belongs to the stress-associated protein （SAP） family with 14 members in Arabidopsis thaliana. SAP12 contains two AN1 zinc fingers and was identified in diagonal 2D redox SDS-PAGE...The stress-associated protein SAP12 belongs to the stress-associated protein （SAP） family with 14 members in Arabidopsis thaliana. SAP12 contains two AN1 zinc fingers and was identified in diagonal 2D redox SDS-PAGE as a protein undergoing major redox-dependent conformational changes. Its transcript was strongly induced under cold and salt stress in a time-dependent manner similar to SAP10, with high levels after 6 h and decreasing levels after 24 and 48 h. The tran- script regulation resembled those of the stress marker peroxiredoxin PrxllD at 24 and 48 h. Recombinant SAP12 protein showed redox-dependent changes in quaternary structure as visualized by altered electrophoretic mobility in non-reducing SDS polyacrylamide gel electrophoresis. The oxidized oligomer was reduced by high dithiothreitol concentrations, and also by E. coli thioredoxin TrxA with low dithiothreitol （DTF） concentrations or NADPH plus NADPH-dependent thioredoxin reductase. From Western blots, the SAP12 protein amount was estimated to be in the range of 0.5 ngμg^-1 leaf protein. SAP12 protein decreased under salt and cold stress. These data suggest a redox state-linked function of SAP12 in plant cells particularly under cold and salt stress.展开更多
The TP53 tumor suppressor gene encodes a DNA-binding transcription factor that regulates multiple cellular processes including cell growth and cell death. The ability of p53 to bind to DNA and activate transcription i...The TP53 tumor suppressor gene encodes a DNA-binding transcription factor that regulates multiple cellular processes including cell growth and cell death. The ability of p53 to bind to DNA and activate transcription is tightly regulated by post-translational modifications and is dependent on a reducing cellular environment. Some p53 transcriptional target genes are involved in regulation of the cellular redox homeostasis, e.g. TIGAR and GLS2. A large fraction of human tumors carry TP53 mutations, most commonly missense mutations that lead to single amino acid substitutions in the core domain. Mutant p53 proteins can acquire so called gain-of-function activities and influence the cellular redox balance in various ways, for instance by binding of the Nrf2 transcription factor, a major regulator of cellular redox state. The DNA-binding core domain of p53 has 10 cysteine residues, three of which participate in holding a zinc atom that is critical for p53 structure and function. Several novel compounds that refold and reactivate missense mutant p53 bind to specific p53 cysteine residues. These compounds can also react with other thiols and target components of the cellular redox system, such as glutathione. Dual targeting of mutant p53 and redox homeostasis may allow more efficient treatment of cancer.展开更多
Citrate synthase has a key role in the tricarboxylic （TCA） cycle of mitochondria of all organisms, as it cata- lyzes the first committed step which is the fusion of a carbon-carbon bond between oxaloacetate and acet...Citrate synthase has a key role in the tricarboxylic （TCA） cycle of mitochondria of all organisms, as it cata- lyzes the first committed step which is the fusion of a carbon-carbon bond between oxaloacetate and acetyl CoA. The regulation of TCA cycle function is especially important in plants, since mitochondrial activities have to be coordinated with photosynthesis. The posttranslational regulation of TCA cycle activity in plants is thus far almost entirely unexplored. Although several TCA cycle enzymes have been identified as thioredoxin targets in vitro, the existence of any thioredoxin-dependent regulation as known for the Calvin cycle, yet remains to be demonstrated. Here we have investigated the redox regulation of the Arabidopsis citrate synthase enzyme by site-directed mutagenesis of its six cysteine residues. Our results indicate that oxidation inhibits the enzyme activity by the formation of mixed disulfides, as the partially oxidized citrate synthase enzyme forms large redox-dependent aggregates. Furthermore, we were able to demonstrate that thioredoxin can cleave diverse intraas well as intermolecular disulfide bridges, which strongly enhances the activity of the enzyme. Activity measurements with the cysteine variants of the enzyme revealed important cysteine residues affecting total enzyme activity as well as the redox sensitivity of the enzyme.展开更多
Thiol-based redox post-translational modifications have emerged as important mechanisms of signaling and regulation in all organisms, and thioredoxin plays a key role by controlling the thiol-disulfide status of targe...Thiol-based redox post-translational modifications have emerged as important mechanisms of signaling and regulation in all organisms, and thioredoxin plays a key role by controlling the thiol-disulfide status of target proteins. Recent redox proteomic studies revealed hundreds of proteins regulated by glutathio- nylation and nitrosylation in the unicellular green alga Chlamydomonas reinhardtii, while much less is known about the thioredoxin interactome in this organism. By combining qualitative and quantitative proteomic analyses, we have comprehensively investigated the Chlamydomonas thioredoxome and 1188 targets have been identified. They participate in a wide range of metabolic pathways and cellular pro- cesses. This study broadens not only the redox regulation to new enzymes involved in well-known thiore- doxin-regulated metabolic pathways but also sheds light on cellular processes for which data supporting redox regulation are scarce （aromatic amino acid biosynthesis, nuclear transport, etc）. Moreover, we char- acterized 1052 thioredoxin-dependent regulatory sites and showed that these data constitute a valuable resource for future functional studies in Chlamydomonas. By comparing this thioredoxome with proteomic data for glutathionylation and nitrosylation at the protein and cysteine levels, this work confirms the existence of a complex redox regulation network in Chlamydomonas and provides evidence of a tremendous selectivity of redox post-translational modifications for specific cysteine residues.展开更多
Lithium-sulfur(Li-S)batteries with high theoretical specific energy are considered to be one of the highly promising next-generation energy storage systems.However,the shuttle effect of lithium polysulfides(LiPSs)and ...Lithium-sulfur(Li-S)batteries with high theoretical specific energy are considered to be one of the highly promising next-generation energy storage systems.However,the shuttle effect of lithium polysulfides(LiPSs)and the interfacial instability of Li anodes have seriously hindered the practical application of Li-S batteries.Optimizing the electrolyte composition with additives can significantly improve the battery performance and has attracted great attention.Herein,we propose an organometallic salt,i.e.,nickel bromide dimethoxyethane(NiBr_(2)DME),as an electrolyte additive,which serves as the dual function of regulating LiPSs redox and synchronously stabilizing Li anodes.We reveal that NiBr_(2)DME can interact with LiPSs via Ni-S and Li-Br bonds,and accelerate the mutual transformation of LiPSs,thus reducing the accumulation of LiPSs in the electrolyte.In addition,NiBr_(2)DME can form a stable LiBr-containing interfacial layer on the Li metal surface,and promote the uniform electrodeposition of Li^(+)ions,and inhibit the formation of Li dendrites.Thus,Li-S batteries with a concentration of 0.5 mmol L^(-1)NiBr_(2)DME show an initial capacity of 919.8 mAh g^(-1)at 0.2 C,and a high capacity retention of 89.3%after 100 cycles.Even at the 4 C rate,a high discharge capacity of 602.9 mAh g^(-1)is achieved.Surprisingly,the good cycling performance is maintained under poor electrolyte conditions with sulfur loading of 4.8 mg cm^(-2)and electrlyte/sulfur ratio of 5µL mg^(-1).This work provides a positive solution to achieve the suppression of shuttle effect,the regulation of LiPSs redox and the stabilization of Li anodes.展开更多
Glycogen constitutes the major carbon storage source in cyanobacteria, as starch in algae and higher plants. Glycogen and starch synthesis is linked to active photosynthesis and both of them are degraded to glucose in...Glycogen constitutes the major carbon storage source in cyanobacteria, as starch in algae and higher plants. Glycogen and starch synthesis is linked to active photosynthesis and both of them are degraded to glucose in the dark to maintain cell metabolism. Control of glycogen biosynthesis in cyanobacteria could be mediated by the regulation of the enzymes involved in this process, ADP-glucose pyrophosphorylase （AGP） and glycogen synthase, which were identified as putative thioredoxin targets. We have analyzed whether both enzymes were subjected to redox modification using purified recombinant enzymes or cell extracts in the model cyanobacterium Synechocystis sp. PCC 6803. Our results indicate that both AGP and glycogen synthases are sensitive to copper oxidation. However, only AGP exhibits a decrease in its enzymatic activity, which is recovered after reduction by DTT or reduced thioredoxin （TrxA）, suggesting a redox control of AGP. In order to elucidate the role in redox control of the cysteine residues present on the AGP sequence （C45, C185, C320, and C337）, they were replaced with serine. All AGP mutant proteins remained active when expressed in Synechocystis, although they showed different electrophoretic mobility profiles after copper oxidation, reflecting a complex pattern of cysteines interaction.展开更多
Photosynthesis involves a series of redox reactions and is the major source of reactive oxygen species in plant cells.Fluctuating light(FL) levels,which occur commonly in natural environments,affect photosynthesis;how...Photosynthesis involves a series of redox reactions and is the major source of reactive oxygen species in plant cells.Fluctuating light(FL) levels,which occur commonly in natural environments,affect photosynthesis;however,little is known about the specific effects of FL on the redox regulation of photosynthesis.Here,we performed global quantitative mapping of the Arabidopsis thaliana cysteine thiol redox proteome under constant light and FL conditions.We identified8857 redox-switched thiols in 4350 proteins,and1501 proteins that are differentially modified depending on light conditions.Notably,proteins related to photosynthesis,especially photosystem I(PSI),are operational thiol-switching hotspots.Exposure of wild-type A.thaliana to FL resulted in decreased PSI abundance,stability,and activity.Interestingly,in response to PSI photodamage,more of the PSI assembly factor PSA3 dynamically switches to the reduced state.Furthermore,the Cys199 and Cys200 sites in PSA3 are necessary for its full function.Moreover,thioredoxin m(Trx m) proteins play roles in redox switching of PSA3,and are required for PSI activity and photosynthesis.This study thus reveals a mechanism for redox-based regulation of PSI under FL,and provides insight into the dynamic acclimation of photosynthesis in a changing environment.展开更多
Photosystem Ⅱ (PSII)core phosphatase (PBCP)selectively dephosphorylates PSII core proteins including D1,D2,CP43,and PsbH.PBCP function is required for efficient degradation of the D1 protein in the repair cycle of PS...Photosystem Ⅱ (PSII)core phosphatase (PBCP)selectively dephosphorylates PSII core proteins including D1,D2,CP43,and PsbH.PBCP function is required for efficient degradation of the D1 protein in the repair cycle of PSII,a supramolecular machinery highly susceptible to photodamage during oxygenic photosynthesis.Here we present structural and functional studies of PBCP from Oryza sativa (OsPBCP).In a symmetrical homodimer of OsPBCP,each monomer contains a PP2C-type phosphatase core domain,a large motif characteristic of PBCPs,and two Small motifs around the active site.The large motif contributes to the formation of a substrate-binding surface groove,and is crucial for the selectivity of PBCP toward PSII core proteins and against the light-harvesting proteins.Remarkably,the phosphatase activity of OsPBCP is strongly inhibited by glutathione and H202.S-Glutathionylation of cysteine residues may introduce steric hindrance and allosteric effects to the active site.Collectively,these results provide detailed mechanistic insights into the substrate selectivity,redox regulation,and catalytic mechanism of PBCP.展开更多
基金University of Burdwan,West Bengal, India, for State Funded Research Fellowship (Grant No. 136/35, 31.07.2014), Government of West Bengal, India
文摘Present work was undertaken to screen some drought tolerant indigenous aromatic rice cultivars(IARCs),commonly cultivated in West Bengal,India,based on their capacity to produce osmolytes,redox-sensitive phenolic acids and flavonoids,as contrivances for redox-regulation under drought stress.Polyethylene glycol induced post imbibitional dehydration stress mediated changes in redox regulatory properties of the germinating seeds of the four IARCs(Jamainadu,Tulaipanji,Sitabhog,Badshabhog),which were assessed in terms of changes in prooxidant accumulation(in-situ localization of reactive oxygen species(ROS)by confocal microscopy,DCFDA(2′,7′-dichlorofluorescin diacetate)oxidation,O2-and H2O2 accumulation),cumulative antioxidative defense(radical scavenging property and total thiol content),ROS scavenging phenolic acids(gallic acid,protocatechuic acid,gentisic acid,para-hydroxy benzoic acid,chlorogenic acid,caffeic acid,syringic acid,salicylic acid,sinapic acid and p-coumaric acid)and flavonoids(catechin,naringin,rutin,quercetin,kaempferol,myricetin and apigenin).The capability of germinating seeds to accumulate osmolytes(like glycinebetaine,proline,soluble carbohydrates and K+ion)and polyphenolic compounds was also correlated with their corresponding redox status and redox biomarkers(conjugated diene,hydroperoxide,thiobarbituric acid reactive substances and free carbonyl content)produced under the same conditions.The results in general showed that accumulation of osmolytes along with the redox-sensitive phenolics and flavonoids conferred the ability to maintain the redox homeostasis under drought stress for the tolerant IARCs(Badshabhog and Tulaipanji).
基金supported by the 863 Program (2006AA060305)China Postdoctoral Science Foundation (20070410196)+1 种基金Jiangsu Province Planned Projects for Postdoctoral Research Funds (0702054C)Jiangsu Province Natural Science Fund (BK2008532)
文摘The durability of three-way catalyst （TWC） and corresponding close-coupled catalyst （CCC） for Euro Ⅳ stage regulation was investigated through Vehicle Road Running Mode tests, whereas emissions of regulated pollutants of three car fleet were investigated at every 100,000 km miles. The results showed that HC, NOx, and CO emission values could meet Euro Ⅳ regulation limits at every point. The redox properties of TWC and CCC were measured by CO reduction during each isothermal. It was obvious that both aged TWC and aged CCC behaved a good redox property at 673 and 773 K. Based on XRD and BET measurement results, TWC and CCC washcoat were characterized with good thermal stability.
基金This study was supported by OTKA(112810)National Excellence Program(126823)Grants awarded to ZR.
文摘MicroRNAs(miRs)are small regulatory RNA transcripts capable of post-transcriptional silencing of mRNA messages by entering a cellular bimolecular apparatus called RNA-induced silencing complex.miRs are involved in the regulation of cellular processes producing,eliminating or repairing the damage caused by reactive oxygen species,and they are active players in redox homeostasis.Increased mitochondrial biogenesis,function and hypertrophy of skeletal muscle are important adaptive responses to regular exercise.In the present review,we highlight some of the redox-sensitive regulatory roles of miRs.
文摘The stress-associated protein SAP12 belongs to the stress-associated protein （SAP） family with 14 members in Arabidopsis thaliana. SAP12 contains two AN1 zinc fingers and was identified in diagonal 2D redox SDS-PAGE as a protein undergoing major redox-dependent conformational changes. Its transcript was strongly induced under cold and salt stress in a time-dependent manner similar to SAP10, with high levels after 6 h and decreasing levels after 24 and 48 h. The tran- script regulation resembled those of the stress marker peroxiredoxin PrxllD at 24 and 48 h. Recombinant SAP12 protein showed redox-dependent changes in quaternary structure as visualized by altered electrophoretic mobility in non-reducing SDS polyacrylamide gel electrophoresis. The oxidized oligomer was reduced by high dithiothreitol concentrations, and also by E. coli thioredoxin TrxA with low dithiothreitol （DTF） concentrations or NADPH plus NADPH-dependent thioredoxin reductase. From Western blots, the SAP12 protein amount was estimated to be in the range of 0.5 ngμg^-1 leaf protein. SAP12 protein decreased under salt and cold stress. These data suggest a redox state-linked function of SAP12 in plant cells particularly under cold and salt stress.
文摘The TP53 tumor suppressor gene encodes a DNA-binding transcription factor that regulates multiple cellular processes including cell growth and cell death. The ability of p53 to bind to DNA and activate transcription is tightly regulated by post-translational modifications and is dependent on a reducing cellular environment. Some p53 transcriptional target genes are involved in regulation of the cellular redox homeostasis, e.g. TIGAR and GLS2. A large fraction of human tumors carry TP53 mutations, most commonly missense mutations that lead to single amino acid substitutions in the core domain. Mutant p53 proteins can acquire so called gain-of-function activities and influence the cellular redox balance in various ways, for instance by binding of the Nrf2 transcription factor, a major regulator of cellular redox state. The DNA-binding core domain of p53 has 10 cysteine residues, three of which participate in holding a zinc atom that is critical for p53 structure and function. Several novel compounds that refold and reactivate missense mutant p53 bind to specific p53 cysteine residues. These compounds can also react with other thiols and target components of the cellular redox system, such as glutathione. Dual targeting of mutant p53 and redox homeostasis may allow more efficient treatment of cancer.
文摘Citrate synthase has a key role in the tricarboxylic （TCA） cycle of mitochondria of all organisms, as it cata- lyzes the first committed step which is the fusion of a carbon-carbon bond between oxaloacetate and acetyl CoA. The regulation of TCA cycle function is especially important in plants, since mitochondrial activities have to be coordinated with photosynthesis. The posttranslational regulation of TCA cycle activity in plants is thus far almost entirely unexplored. Although several TCA cycle enzymes have been identified as thioredoxin targets in vitro, the existence of any thioredoxin-dependent regulation as known for the Calvin cycle, yet remains to be demonstrated. Here we have investigated the redox regulation of the Arabidopsis citrate synthase enzyme by site-directed mutagenesis of its six cysteine residues. Our results indicate that oxidation inhibits the enzyme activity by the formation of mixed disulfides, as the partially oxidized citrate synthase enzyme forms large redox-dependent aggregates. Furthermore, we were able to demonstrate that thioredoxin can cleave diverse intraas well as intermolecular disulfide bridges, which strongly enhances the activity of the enzyme. Activity measurements with the cysteine variants of the enzyme revealed important cysteine residues affecting total enzyme activity as well as the redox sensitivity of the enzyme.
文摘Thiol-based redox post-translational modifications have emerged as important mechanisms of signaling and regulation in all organisms, and thioredoxin plays a key role by controlling the thiol-disulfide status of target proteins. Recent redox proteomic studies revealed hundreds of proteins regulated by glutathio- nylation and nitrosylation in the unicellular green alga Chlamydomonas reinhardtii, while much less is known about the thioredoxin interactome in this organism. By combining qualitative and quantitative proteomic analyses, we have comprehensively investigated the Chlamydomonas thioredoxome and 1188 targets have been identified. They participate in a wide range of metabolic pathways and cellular pro- cesses. This study broadens not only the redox regulation to new enzymes involved in well-known thiore- doxin-regulated metabolic pathways but also sheds light on cellular processes for which data supporting redox regulation are scarce （aromatic amino acid biosynthesis, nuclear transport, etc）. Moreover, we char- acterized 1052 thioredoxin-dependent regulatory sites and showed that these data constitute a valuable resource for future functional studies in Chlamydomonas. By comparing this thioredoxome with proteomic data for glutathionylation and nitrosylation at the protein and cysteine levels, this work confirms the existence of a complex redox regulation network in Chlamydomonas and provides evidence of a tremendous selectivity of redox post-translational modifications for specific cysteine residues.
基金supported by the Jiangxi Province Leading Talent Project for Academic and Technical Leaders in Major Disciplines(20213BCJ22024)National Natural Science Foundation of China(22269013,22263009 and 21863006)+1 种基金Natural Science Foundation of Jiangxi Province(20224ACB213001 and 20212BBE53051)Elite Scientists Sponsorship Program by Jiangxi Association for Science and Technology(2023QT07)。
文摘Lithium-sulfur(Li-S)batteries with high theoretical specific energy are considered to be one of the highly promising next-generation energy storage systems.However,the shuttle effect of lithium polysulfides(LiPSs)and the interfacial instability of Li anodes have seriously hindered the practical application of Li-S batteries.Optimizing the electrolyte composition with additives can significantly improve the battery performance and has attracted great attention.Herein,we propose an organometallic salt,i.e.,nickel bromide dimethoxyethane(NiBr_(2)DME),as an electrolyte additive,which serves as the dual function of regulating LiPSs redox and synchronously stabilizing Li anodes.We reveal that NiBr_(2)DME can interact with LiPSs via Ni-S and Li-Br bonds,and accelerate the mutual transformation of LiPSs,thus reducing the accumulation of LiPSs in the electrolyte.In addition,NiBr_(2)DME can form a stable LiBr-containing interfacial layer on the Li metal surface,and promote the uniform electrodeposition of Li^(+)ions,and inhibit the formation of Li dendrites.Thus,Li-S batteries with a concentration of 0.5 mmol L^(-1)NiBr_(2)DME show an initial capacity of 919.8 mAh g^(-1)at 0.2 C,and a high capacity retention of 89.3%after 100 cycles.Even at the 4 C rate,a high discharge capacity of 602.9 mAh g^(-1)is achieved.Surprisingly,the good cycling performance is maintained under poor electrolyte conditions with sulfur loading of 4.8 mg cm^(-2)and electrlyte/sulfur ratio of 5µL mg^(-1).This work provides a positive solution to achieve the suppression of shuttle effect,the regulation of LiPSs redox and the stabilization of Li anodes.
文摘Glycogen constitutes the major carbon storage source in cyanobacteria, as starch in algae and higher plants. Glycogen and starch synthesis is linked to active photosynthesis and both of them are degraded to glucose in the dark to maintain cell metabolism. Control of glycogen biosynthesis in cyanobacteria could be mediated by the regulation of the enzymes involved in this process, ADP-glucose pyrophosphorylase （AGP） and glycogen synthase, which were identified as putative thioredoxin targets. We have analyzed whether both enzymes were subjected to redox modification using purified recombinant enzymes or cell extracts in the model cyanobacterium Synechocystis sp. PCC 6803. Our results indicate that both AGP and glycogen synthases are sensitive to copper oxidation. However, only AGP exhibits a decrease in its enzymatic activity, which is recovered after reduction by DTT or reduced thioredoxin （TrxA）, suggesting a redox control of AGP. In order to elucidate the role in redox control of the cysteine residues present on the AGP sequence （C45, C185, C320, and C337）, they were replaced with serine. All AGP mutant proteins remained active when expressed in Synechocystis, although they showed different electrophoretic mobility profiles after copper oxidation, reflecting a complex pattern of cysteines interaction.
基金supported by the National Natural Science Foundation of China Grant (31970261)the Talent Support Project of Guangdong (2019TQ05N182)。
文摘Photosynthesis involves a series of redox reactions and is the major source of reactive oxygen species in plant cells.Fluctuating light(FL) levels,which occur commonly in natural environments,affect photosynthesis;however,little is known about the specific effects of FL on the redox regulation of photosynthesis.Here,we performed global quantitative mapping of the Arabidopsis thaliana cysteine thiol redox proteome under constant light and FL conditions.We identified8857 redox-switched thiols in 4350 proteins,and1501 proteins that are differentially modified depending on light conditions.Notably,proteins related to photosynthesis,especially photosystem I(PSI),are operational thiol-switching hotspots.Exposure of wild-type A.thaliana to FL resulted in decreased PSI abundance,stability,and activity.Interestingly,in response to PSI photodamage,more of the PSI assembly factor PSA3 dynamically switches to the reduced state.Furthermore,the Cys199 and Cys200 sites in PSA3 are necessary for its full function.Moreover,thioredoxin m(Trx m) proteins play roles in redox switching of PSA3,and are required for PSI activity and photosynthesis.This study thus reveals a mechanism for redox-based regulation of PSI under FL,and provides insight into the dynamic acclimation of photosynthesis in a changing environment.
基金the National Key R&D Program of China (2017YFA0503702)the Strategic Priority Research Program of CAS (XDB08020302)+1 种基金the Key Research Program of Frontier Sciences of CAS (QYZDB-SSW-SMC005)the National Natural Science Foundation of China (31670749).
文摘Photosystem Ⅱ (PSII)core phosphatase (PBCP)selectively dephosphorylates PSII core proteins including D1,D2,CP43,and PsbH.PBCP function is required for efficient degradation of the D1 protein in the repair cycle of PSII,a supramolecular machinery highly susceptible to photodamage during oxygenic photosynthesis.Here we present structural and functional studies of PBCP from Oryza sativa (OsPBCP).In a symmetrical homodimer of OsPBCP,each monomer contains a PP2C-type phosphatase core domain,a large motif characteristic of PBCPs,and two Small motifs around the active site.The large motif contributes to the formation of a substrate-binding surface groove,and is crucial for the selectivity of PBCP toward PSII core proteins and against the light-harvesting proteins.Remarkably,the phosphatase activity of OsPBCP is strongly inhibited by glutathione and H202.S-Glutathionylation of cysteine residues may introduce steric hindrance and allosteric effects to the active site.Collectively,these results provide detailed mechanistic insights into the substrate selectivity,redox regulation,and catalytic mechanism of PBCP.
