LHCII is a crucial light-harvesting pigment/protein complex in photosystem II (PSII) supercomplex. It also participates in the light energy redistribution between photosystems and in the photoprotection via its revers...LHCII is a crucial light-harvesting pigment/protein complex in photosystem II (PSII) supercomplex. It also participates in the light energy redistribution between photosystems and in the photoprotection via its reversible dissociation with PSII and PSI (photosystem I). This reversible detachment of LHCII is regulated by phosphorylation of its own and PSII core protein. Under low light conditions, LHCII is phosphorylated and dissociated with PSII core protein complex and combined with PSI, which balances the excitation energy between PSII and PSI;Under high light environment, the phosphorylation of PSII core proteins makes LHCII detach from PSII. The dissociated LHCII presents in a free state, which involves in the thermal dissipation of excess excitation energy. During photodamage, dual phosphorylations of both PSII core proteins and LHCII complexes occur. The phosphorylation of D1 is conductive to the disintegration of photodamaged PSII and the cycle of repair. In this circumstance, the phosphorylation of LHCII is induced by reactive oxygen species (ROS) and then the phosphorylated LHCII migrates to PSI, into the repair cycle of damaged PSII. The ferredoxin (Fdr) and thioredoxin (Tdr) system may play a possible central role in the phosphorylation regulation on LHCII dissociation.展开更多
State transition is an important protection mechanism of plants for maintaining optimal efficiency through redistributing unbalanced excitation energy between photosystem II （PSII） and photosystem I （PSI）. This pr...State transition is an important protection mechanism of plants for maintaining optimal efficiency through redistributing unbalanced excitation energy between photosystem II （PSII） and photosystem I （PSI）. This process depends on the reversible phosphorylation/dephosphorylation of the major light-harvesting complex II （LHCII） and its bi-directional migration between PSII and PSI. But it remains unclear how phosphorylation/dephosphorylation modulates the LHCII conformation and further regulates its reversible migration. Here molecular dynamics simulations （MDS） were employed to elucidate the impact of phosphorylation on LHCII conformation. The results indicated that N-terminal phosphorylation loosened LHCII trimer with decreased hydrogen bond （H-bond） interactions and extended the distances between neighboring monomers, which stemmed from the conformational ad- justment of each monomer itself. Global conformational change of LHCII monomer started from its stromal N- terminal （including the phosphorylation sites） by enhancing its interaction to lipid membrane and by adjusting the interaction network with surrounded inter-monomer andintra-monomer transmembrane helixes of B, C, and A, and finally triggered the reorientation of transmembrane helixes and transferred the conformational change to luminal side helixes and loops. These results further our understanding in molecular mechanism of LHCII migration during state transition from the phosphorylation-induced microstructural feature of LHCII.展开更多
In Arabidopsis thaliana, STN7 kinase is required for phosphorylation of LHCII and for state transitions. In this paper, a hydrophilic polypeptide, derived from the amino acid sequence of STN7, was conjugated to a carr...In Arabidopsis thaliana, STN7 kinase is required for phosphorylation of LHCII and for state transitions. In this paper, a hydrophilic polypeptide, derived from the amino acid sequence of STN7, was conjugated to a carrier protein, bovine serum albumin (BSA), to obtain the polyclonal antibody. Immunogenicity and specificity of the polyclonal antibody were evaluated by agar gel immunodiffusion (AGID) test and Western blot analysis. The results show that besides the phosphorylation of LHCII proteins, also the expression of STN7 was regulated by temperature conditions. In addition, the change tendency of LHCII proteins phosphorylation was not only coherent with expression of STN7 with respect to increasing temperature, but also closely related to state transitions. These results would provide useful information for studying regulatory mechanism of LHCII proteins phosphorylation and expression of STN7.展开更多
In plant chloroplasts,photosystem II(PSII)complexes,together with light-harvesting complex II(LHCII),form various PSII-LHCII supercomplexes(SCs).This process likely involves immunophilins,but the underlying regulatory...In plant chloroplasts,photosystem II(PSII)complexes,together with light-harvesting complex II(LHCII),form various PSII-LHCII supercomplexes(SCs).This process likely involves immunophilins,but the underlying regulatory mechanisms are unclear.Here,by comparing Arabidopsis thaliana mutants lacking the chloroplast lumen-localized immunophilin CYCLOPHILIN28(CYP28)to wildtype and transgenic complemented lines,we determined that CYP28 regulates the assembly and accumulation of PSII-LHCII SCs.Compared to the wild type,cyp28 plants showed accelerated leaf growth,earlier flowering time,and enhanced accumulation of high molecular weight PSII-LHCII SCs under normal light conditions.The lack of CYP28 also significantly affected the electron transport rate.Blue native-polyacrylamide gel electrophoresis analysis revealed more Lhcb6 and less Lhcb4 in M-LHCII-Lhcb4-Lhcb6 complexes in cyp28 versus wild-type plants.Peptidyl-prolyl cis/trans isomerase(PPIase)activity assays revealed that CYP28 exhibits weak PPIase activity and that its K113 and E187 residues are critical for this activity.Mutant analysis suggested that CYP28 may regulate PSIILHCII SC accumulation by altering the configuration of Lhcb6 via its PPIase activity.Furthermore,the Lhcb6-P139 residue is critical for PSII-LHCII SC assembly and accumulation.Therefore,our findings suggest that CYP28 likely regulates PSII-LHCII SC assembly and accumulation by altering the configuration of P139 of Lhcb6 via its PPIase activity.展开更多
Funded by the National Natural Science Foundation of China,Chinese Ministry of Science and Technology,and Chinese Academy of Sciences,ajoint team of three laboratories from the Institute of Biophysics of Chinese Acade...Funded by the National Natural Science Foundation of China,Chinese Ministry of Science and Technology,and Chinese Academy of Sciences,ajoint team of three laboratories from the Institute of Biophysics of Chinese Academy of Sciences,namely Liu Zhenfeng’s(柳振峰),Zhang展开更多
文摘LHCII is a crucial light-harvesting pigment/protein complex in photosystem II (PSII) supercomplex. It also participates in the light energy redistribution between photosystems and in the photoprotection via its reversible dissociation with PSII and PSI (photosystem I). This reversible detachment of LHCII is regulated by phosphorylation of its own and PSII core protein. Under low light conditions, LHCII is phosphorylated and dissociated with PSII core protein complex and combined with PSI, which balances the excitation energy between PSII and PSI;Under high light environment, the phosphorylation of PSII core proteins makes LHCII detach from PSII. The dissociated LHCII presents in a free state, which involves in the thermal dissipation of excess excitation energy. During photodamage, dual phosphorylations of both PSII core proteins and LHCII complexes occur. The phosphorylation of D1 is conductive to the disintegration of photodamaged PSII and the cycle of repair. In this circumstance, the phosphorylation of LHCII is induced by reactive oxygen species (ROS) and then the phosphorylated LHCII migrates to PSI, into the repair cycle of damaged PSII. The ferredoxin (Fdr) and thioredoxin (Tdr) system may play a possible central role in the phosphorylation regulation on LHCII dissociation.
基金supported by the National Key Basic Research Foundation of China(2006CB910303 and 2011CB710904)the National Natural Science Foundation of China(11072251 and31230027)+1 种基金the CAS Knowledge Innovation Program(KJCX2YW-L08)the Scientific Research Equipment Project(Y2010030)
文摘State transition is an important protection mechanism of plants for maintaining optimal efficiency through redistributing unbalanced excitation energy between photosystem II （PSII） and photosystem I （PSI）. This process depends on the reversible phosphorylation/dephosphorylation of the major light-harvesting complex II （LHCII） and its bi-directional migration between PSII and PSI. But it remains unclear how phosphorylation/dephosphorylation modulates the LHCII conformation and further regulates its reversible migration. Here molecular dynamics simulations （MDS） were employed to elucidate the impact of phosphorylation on LHCII conformation. The results indicated that N-terminal phosphorylation loosened LHCII trimer with decreased hydrogen bond （H-bond） interactions and extended the distances between neighboring monomers, which stemmed from the conformational ad- justment of each monomer itself. Global conformational change of LHCII monomer started from its stromal N- terminal （including the phosphorylation sites） by enhancing its interaction to lipid membrane and by adjusting the interaction network with surrounded inter-monomer andintra-monomer transmembrane helixes of B, C, and A, and finally triggered the reorientation of transmembrane helixes and transferred the conformational change to luminal side helixes and loops. These results further our understanding in molecular mechanism of LHCII migration during state transition from the phosphorylation-induced microstructural feature of LHCII.
基金the National Natural Sciences Foundation of China (Grant No. 30270124)Doctoral Foundation of Ministry of Education of China (Grant No. 20020610094)+1 种基金Program for New Century Excellent Talents in University (Grant No. NCET-04-0861)Sichuan University Research Grant 985
文摘In Arabidopsis thaliana, STN7 kinase is required for phosphorylation of LHCII and for state transitions. In this paper, a hydrophilic polypeptide, derived from the amino acid sequence of STN7, was conjugated to a carrier protein, bovine serum albumin (BSA), to obtain the polyclonal antibody. Immunogenicity and specificity of the polyclonal antibody were evaluated by agar gel immunodiffusion (AGID) test and Western blot analysis. The results show that besides the phosphorylation of LHCII proteins, also the expression of STN7 was regulated by temperature conditions. In addition, the change tendency of LHCII proteins phosphorylation was not only coherent with expression of STN7 with respect to increasing temperature, but also closely related to state transitions. These results would provide useful information for studying regulatory mechanism of LHCII proteins phosphorylation and expression of STN7.
基金supported by the National Natural Science Foundation of China(31700206)the Natural Science Basic Research Program of Shaanxi(2016JM3023)the Special Scientific Research Project of Education Department of Shaanxi Province(16JK1792)。
文摘In plant chloroplasts,photosystem II(PSII)complexes,together with light-harvesting complex II(LHCII),form various PSII-LHCII supercomplexes(SCs).This process likely involves immunophilins,but the underlying regulatory mechanisms are unclear.Here,by comparing Arabidopsis thaliana mutants lacking the chloroplast lumen-localized immunophilin CYCLOPHILIN28(CYP28)to wildtype and transgenic complemented lines,we determined that CYP28 regulates the assembly and accumulation of PSII-LHCII SCs.Compared to the wild type,cyp28 plants showed accelerated leaf growth,earlier flowering time,and enhanced accumulation of high molecular weight PSII-LHCII SCs under normal light conditions.The lack of CYP28 also significantly affected the electron transport rate.Blue native-polyacrylamide gel electrophoresis analysis revealed more Lhcb6 and less Lhcb4 in M-LHCII-Lhcb4-Lhcb6 complexes in cyp28 versus wild-type plants.Peptidyl-prolyl cis/trans isomerase(PPIase)activity assays revealed that CYP28 exhibits weak PPIase activity and that its K113 and E187 residues are critical for this activity.Mutant analysis suggested that CYP28 may regulate PSIILHCII SC accumulation by altering the configuration of Lhcb6 via its PPIase activity.Furthermore,the Lhcb6-P139 residue is critical for PSII-LHCII SC assembly and accumulation.Therefore,our findings suggest that CYP28 likely regulates PSII-LHCII SC assembly and accumulation by altering the configuration of P139 of Lhcb6 via its PPIase activity.
文摘Funded by the National Natural Science Foundation of China,Chinese Ministry of Science and Technology,and Chinese Academy of Sciences,ajoint team of three laboratories from the Institute of Biophysics of Chinese Academy of Sciences,namely Liu Zhenfeng’s(柳振峰),Zhang
