The techniques of oxygen electrode polarography and Fourier transform infrared (FT IR) spectroscopy were employed to explore the involvement of digalactosyl diacylglycerol (DGDG) in functional and structural roles in...The techniques of oxygen electrode polarography and Fourier transform infrared (FT IR) spectroscopy were employed to explore the involvement of digalactosyl diacylglycerol (DGDG) in functional and structural roles in the photosystem II core complex (PSIICC). It was shown that DGDG exhibited the ability to stimulate the oxygen evolution in PSIICC, which was accompanied by the changes in the structures of PSIICC proteins. The results revealed that there existed hydrogen bonding interactions between DGDG molecules and PSIICC proteins. It is most likely that the sites of PSIICC interaction with DGDG are in the extrinsic protein of 33 kDa.展开更多
So far it is unclear whether the release of oxygen-evolving complex （OEC） subunits including PsbO, PsbP, and PsbQ proteins is affected by the phosphorylation of photosystem II （PSII） membranes under light stress. ...So far it is unclear whether the release of oxygen-evolving complex （OEC） subunits including PsbO, PsbP, and PsbQ proteins is affected by the phosphorylation of photosystem II （PSII） membranes under light stress. In this work, different phosphorylated PSII membranes were obtained from spinach. Phosphorylation partially suppressed the release of PsbO, PsbP, and PsbQ proteins from PSII membranes under light stress. Reactive oxygen species including superoxide anion, hydrogen peroxide and hydroxyl radical, were involved in the release of a small part of PsbO protein, but not in the release of PsbP and PsbQ proteins in the non-phosphorylated and phosphorylated PSII membranes. All of the results suggested that the release of PsbO, PsbP, and PsbQ proteins was partially regulated by phosphorylation in PSII membranes, and the role of reactive oxygen species in the release of OEC subunits in non-phosphorylated PSII membranes was the same as in phosphorylated PSII membranes.展开更多
The influence of digalactosyldiacylglycerol (DGDG), one of the photosynthetic membrane lipids, on heat inactivation of the process of oxygen evolution has been studied in vitro in photosystem Ⅱ(PS Ⅱ) core complex. I...The influence of digalactosyldiacylglycerol (DGDG), one of the photosynthetic membrane lipids, on heat inactivation of the process of oxygen evolution has been studied in vitro in photosystem Ⅱ(PS Ⅱ) core complex. It was found that the temperature of semi-inactivation of oxygen evolution in the complex increased from 40.0 to about 43.0℃ in the presence of DGDG with 5-min heat treatment in the dark. Furthermore, when PS Ⅱ core complex was incubated for 5 min at 45.0℃, the oxygen evolution in the complex was completely lost, whilst the DGDG-complexed PS Ⅱ core complex still retained a 16% of activity (100% for 25.0℃). In addition, a 1-h incubation at 38.0℃ inactivated absolutely the oxygen evolution for the PS Ⅱ core complex. By contrast, there remained about 20% of activity (zero time for 100%) for the complex in the presence of DGDG under the same condition. These results indicate a new role of DGDG in the protection of PS Ⅱ core complex against the deleterious effects of temperature. It was展开更多
The techniques of oxygen electrode polarogra-phy and Fourier transform infrared (FT-IR) spectroscopy were employed to explore the roles of polar head-group of phosphatidylglycerol (PG) molecules in the functional and ...The techniques of oxygen electrode polarogra-phy and Fourier transform infrared (FT-IR) spectroscopy were employed to explore the roles of polar head-group of phosphatidylglycerol (PG) molecules in the functional and structural aspects of photosystem Ⅱ (PS Ⅱ) through enzymatic approach. It was shown that the depletion of PG by treatment of phospholipase C (PLC) on PS Ⅱ particles caused the inhibition of oxygen evolving activity in PS Ⅱ. This effect also gave rise to changes in the protein secondary structures of PS Ⅱ, that is, an increase in a-helical conformation which is compensated by the loss of p-strand structures. It revealed that the head-group of PG molecules plays an important structural role in the maintenance of normal structure of PS Ⅱ proteins, which is required to maintain the appropriate physiological activity of the PS Ⅱ complex such as the oxygen evolving activity. It is suggested that there most probably exist hydrogen-bonding interactions between PG molecules and PS Ⅱ proteins.展开更多
So far, many important questions and problems concerning the structure and mechanism of photosynthetic oxygen evolution are still unsolved. On the basis of recent achievements in this field, a new structure model is p...So far, many important questions and problems concerning the structure and mechanism of photosynthetic oxygen evolution are still unsolved. On the basis of recent achievements in this field, a new structure model is proposed whereby two H2O molecules bind asymmetrically to two manganese ions (Mn1Ⅱ and Mn4Ⅲ) at the open end of 'C' shaped cluster and keep rather large distance. Two histidine residues coordinate to the other two manganese ions in higher oxi-展开更多
Effects of Photosystem Ⅱ (PS Ⅱ) extrinsic polypeptides of oxygen-evolving complex and manganese clusters on PS Ⅱ carbonic anhydrase (CA) were studied with spinach PS Ⅱ membranes. The result supported that membrane...Effects of Photosystem Ⅱ (PS Ⅱ) extrinsic polypeptides of oxygen-evolving complex and manganese clusters on PS Ⅱ carbonic anhydrase (CA) were studied with spinach PS Ⅱ membranes. The result supported that membrane-bound CA is located in the donor side of PS Ⅱ. The extrinsic polypeptides played an important role of maintaining CA activity. After removing manganese clusters, oxygen evolution activity was inhibited, but PSⅡ-CA activity was unchanged. It was concluded that CA activity is independent of the presence of manganese clusters, and was not directly correlated with oxygen evolution activity.展开更多
The roles of a tomato （Lycopersicon esculentum） chloroplast-targeted DnaJ protein （LeCDJ1） were investigat-ed using wild-type （WT） and sense transgenic tomatoes. The LeCDJ1 expression was upregulated by 38℃, 42...The roles of a tomato （Lycopersicon esculentum） chloroplast-targeted DnaJ protein （LeCDJ1） were investigat-ed using wild-type （WT） and sense transgenic tomatoes. The LeCDJ1 expression was upregulated by 38℃, 42 ℃, 45 ℃, NaCl, PEG, methyl viologen （MV） and hydrogen peroxide （H2O2）, but not by 30 ℃ and 35 ℃. Meanwhile, LeCDJ1 was involved in the response of plants to abscisic acid （ABA）. Under heat stress, the sense plants showed better growth, higher chlorophyll content, lower malondialdehyde （MDA） accumulation and relative electrical conductivity （REC）, and also less PSII photoinhibition than WT. Interestingly, the sense plants treated with streptomycin （SM）, an inhibitor of organellar translation, still showed higher maximum photo-chemistry efficiency of PSII （Fv/Fm） and D1 protein levels than the SM-untreated WT, suggesting that the protective effect of LeCDJ1 on PSII was, at least partially, independent of D1＆amp;nbsp;protein synthesis. Furthermore, the relatively lower super-oxide radical （O2^＊-） and H2O2 levels in the sense plants were considered to be due to the higher ascorbate peroxidase （APX） and superoxide dismutase （SOD） activity, which seemed unlikely dependent on their transcription level. These results indicated that LeCDJ1 overexpression facilitated heat tolerance in transgenic tomatoes.展开更多
文摘The techniques of oxygen electrode polarography and Fourier transform infrared (FT IR) spectroscopy were employed to explore the involvement of digalactosyl diacylglycerol (DGDG) in functional and structural roles in the photosystem II core complex (PSIICC). It was shown that DGDG exhibited the ability to stimulate the oxygen evolution in PSIICC, which was accompanied by the changes in the structures of PSIICC proteins. The results revealed that there existed hydrogen bonding interactions between DGDG molecules and PSIICC proteins. It is most likely that the sites of PSIICC interaction with DGDG are in the extrinsic protein of 33 kDa.
基金Project supported by the National Natural Science Foundation of China （Nos. 20875093 and 90813021） and the Pilot Project of Knowledge Innovation Program of the Chinese Academy of Sciences （No. KJCX2-SW-w29）.
文摘So far it is unclear whether the release of oxygen-evolving complex （OEC） subunits including PsbO, PsbP, and PsbQ proteins is affected by the phosphorylation of photosystem II （PSII） membranes under light stress. In this work, different phosphorylated PSII membranes were obtained from spinach. Phosphorylation partially suppressed the release of PsbO, PsbP, and PsbQ proteins from PSII membranes under light stress. Reactive oxygen species including superoxide anion, hydrogen peroxide and hydroxyl radical, were involved in the release of a small part of PsbO protein, but not in the release of PsbP and PsbQ proteins in the non-phosphorylated and phosphorylated PSII membranes. All of the results suggested that the release of PsbO, PsbP, and PsbQ proteins was partially regulated by phosphorylation in PSII membranes, and the role of reactive oxygen species in the release of OEC subunits in non-phosphorylated PSII membranes was the same as in phosphorylated PSII membranes.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 39890390)the State Basic Research Development Plan of China (Grant No. G1998010100)the Innovative Foundation of Laboratory of Photosynthesis Basic Research, In
文摘The influence of digalactosyldiacylglycerol (DGDG), one of the photosynthetic membrane lipids, on heat inactivation of the process of oxygen evolution has been studied in vitro in photosystem Ⅱ(PS Ⅱ) core complex. It was found that the temperature of semi-inactivation of oxygen evolution in the complex increased from 40.0 to about 43.0℃ in the presence of DGDG with 5-min heat treatment in the dark. Furthermore, when PS Ⅱ core complex was incubated for 5 min at 45.0℃, the oxygen evolution in the complex was completely lost, whilst the DGDG-complexed PS Ⅱ core complex still retained a 16% of activity (100% for 25.0℃). In addition, a 1-h incubation at 38.0℃ inactivated absolutely the oxygen evolution for the PS Ⅱ core complex. By contrast, there remained about 20% of activity (zero time for 100%) for the complex in the presence of DGDG under the same condition. These results indicate a new role of DGDG in the protection of PS Ⅱ core complex against the deleterious effects of temperature. It was
基金This work was supported by the National Natural Science Foundation of China (Grant No. 39890390) the State Basic Research Development Plan of China (Grant No. G1998010100)the Innovative Foundation of Laboratory of Photosynthesis Basic Research, Insti
文摘The techniques of oxygen electrode polarogra-phy and Fourier transform infrared (FT-IR) spectroscopy were employed to explore the roles of polar head-group of phosphatidylglycerol (PG) molecules in the functional and structural aspects of photosystem Ⅱ (PS Ⅱ) through enzymatic approach. It was shown that the depletion of PG by treatment of phospholipase C (PLC) on PS Ⅱ particles caused the inhibition of oxygen evolving activity in PS Ⅱ. This effect also gave rise to changes in the protein secondary structures of PS Ⅱ, that is, an increase in a-helical conformation which is compensated by the loss of p-strand structures. It revealed that the head-group of PG molecules plays an important structural role in the maintenance of normal structure of PS Ⅱ proteins, which is required to maintain the appropriate physiological activity of the PS Ⅱ complex such as the oxygen evolving activity. It is suggested that there most probably exist hydrogen-bonding interactions between PG molecules and PS Ⅱ proteins.
文摘So far, many important questions and problems concerning the structure and mechanism of photosynthetic oxygen evolution are still unsolved. On the basis of recent achievements in this field, a new structure model is proposed whereby two H2O molecules bind asymmetrically to two manganese ions (Mn1Ⅱ and Mn4Ⅲ) at the open end of 'C' shaped cluster and keep rather large distance. Two histidine residues coordinate to the other two manganese ions in higher oxi-
基金State Key Basic Research Development Plan (Grant No. G1998010100) and the National Natural Science Foundation of China (Grant No. 39770156).
文摘Effects of Photosystem Ⅱ (PS Ⅱ) extrinsic polypeptides of oxygen-evolving complex and manganese clusters on PS Ⅱ carbonic anhydrase (CA) were studied with spinach PS Ⅱ membranes. The result supported that membrane-bound CA is located in the donor side of PS Ⅱ. The extrinsic polypeptides played an important role of maintaining CA activity. After removing manganese clusters, oxygen evolution activity was inhibited, but PSⅡ-CA activity was unchanged. It was concluded that CA activity is independent of the presence of manganese clusters, and was not directly correlated with oxygen evolution activity.
基金supported by the State Key Basic Research and Development Plan of China(2009CB118505)the Natural Science Foundation of China(31071338,31171474)
文摘The roles of a tomato （Lycopersicon esculentum） chloroplast-targeted DnaJ protein （LeCDJ1） were investigat-ed using wild-type （WT） and sense transgenic tomatoes. The LeCDJ1 expression was upregulated by 38℃, 42 ℃, 45 ℃, NaCl, PEG, methyl viologen （MV） and hydrogen peroxide （H2O2）, but not by 30 ℃ and 35 ℃. Meanwhile, LeCDJ1 was involved in the response of plants to abscisic acid （ABA）. Under heat stress, the sense plants showed better growth, higher chlorophyll content, lower malondialdehyde （MDA） accumulation and relative electrical conductivity （REC）, and also less PSII photoinhibition than WT. Interestingly, the sense plants treated with streptomycin （SM）, an inhibitor of organellar translation, still showed higher maximum photo-chemistry efficiency of PSII （Fv/Fm） and D1 protein levels than the SM-untreated WT, suggesting that the protective effect of LeCDJ1 on PSII was, at least partially, independent of D1＆amp;nbsp;protein synthesis. Furthermore, the relatively lower super-oxide radical （O2^＊-） and H2O2 levels in the sense plants were considered to be due to the higher ascorbate peroxidase （APX） and superoxide dismutase （SOD） activity, which seemed unlikely dependent on their transcription level. These results indicated that LeCDJ1 overexpression facilitated heat tolerance in transgenic tomatoes.
