• Journal of Plant Biology
• /
• v.33 no.4
• /
• pp.277-283
• /
• 1990

Inactivation and reactivation of photosynthetic oxygen evolving complex were studied with isolated spinach (Spinacia oleraceda. L.) photosystem II particles by the activity of oxygen evolution and chlorophyll fluorescence. When the particles were treated with Tris and urea, the oxygen evolution was inactivated and three polypeptides having molecular weights of 33 kDa, 24 kDa and 18 kDa were simultaneously released. But in NaCl-treated particles, two polypeptides of 24 kDa and 18 kDa were removed from PS II particles. The oxygen evolution activities of Tris and urea-treated particles were not restored by adding cation ions (Mg2+, Mn2+ and Ca2+), but the NaCl-treated particles were restored by exogenously added Ca2+. The removal of these extrinsic polypeptides, especially 33 kDa, markedly showed the decrease of the variable fluorescence (Fv). These results are likely to be due to dissipate thermal energy by antenna of photosystem II complexes.

• Journal of Photoscience
• /
• v.3 no.1
• /
• pp.23-28
• /
• 1996

To investigate the structure and function of photosystem I, cartridge mutagenesis technique was used to inactivate the psaB gene of photosystem I. From the screen, many strains which have potential defects in photosystem I were generated. Biochemical analysis revealed that B2, one of the mutant, had a reduced amount of chlorophyll. Electron transfer activitx from photosystem II to photosystem I as oxygen uptake was the rate of 64 % of wild type. Also B2 showed a decreased photosystem I activity when measured by 77 K fluorescence emission spectrum. Particularly, immunodetection analysis showed that the B2 had reduced amount of PsaA/PsaB, but a normal range of PsaC and PsaD. Here we present a photoheterotrophic mutant for psaB gene as a unique model strain for future study of structural/functional relationship and biogenesis of photosystem I.

• BMB Reports
• /
• v.32 no.2
• /
• pp.189-195
• /
• 1999

From the Panax ginseng chloroplast, the psbE and psbF genes, encoding the $\alpha$- and $\beta$-subunits of cytochrome b-559 of the photosystem II reaction center, respectively, were cloned and characterized. The psbE and psbF genes were composed of 252 and 117 nucleotides, respectively. The deduced amino acid sequence of the $\alpha$-subunits showed 95%, 93%, and 91% homology to monocots, dicots, and liverwort, respectively, whereas the $\beta$-subunits showed approximately 98% to 95% homology to the same species. Southern blot analysis revealed that a single copy of the psbEF gene exists in the chloroplast plastid. Northern blot analysis indicated that the psbE and psbF genes are cotranscribed as a polycistron.

• BMB Reports
• /
• v.40 no.5
• /
• pp.644-648
• /
• 2007

Exposure of algae or plants to irradiance from above the light saturation point of photosynthesis is known as high light stress. This high light stress induces various responses including photoinhibition of the photosynthetic apparatus. The degree of photoinhibition could be clearly determined by measuring the parameters such as absorption and fluorescence of chromoproteins. In cyanobacteria and red algae, most of the photosystem (PS) II associated light harvesting is performed by a membrane attached complex called the phycobilisome (PBS). The effects of high intensity light (1000-4000 ${\mu}mol$ photons $m^{-2}s^{-1}$) on excitation energy transfer from PBSs to PS II in a cyanobacterium Spirulina platensis were studied by measuring room temperature PC fluorescence emission spectra. High light (3000 ${\mu}mol$ photons $m^{-2}s^{-1}$) stress had a significant effect on PC fluorescence emission spectra. On the other hand, light stress induced an increase in the ratio of PC fluorescence intensity of PBS indicating that light stress inhibits excitation energy transfer from PBS to PS II. The high light treatment to 3000 ${\mu}mol$ photons $m^{-2}s^{-1}$ caused disappearance of 31.5 kDa linker polypeptide which is known to link PC discs together. In addition we observed the similar decrease in the other polypeptide contents. Our data concludes that the Spirulina cells upon light treatment causes alterations in the phycobiliproteins (PBPs) and affects the energy transfer process within the PBSs.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.6
• /
• pp.1479-1484
• /
• 2010

Photosynthesis uses light energy to drive the oxidation of water at an oxygen-evolving catalytic site within photosystem II (PSII). Chlorophyll binding by the photosystem II subunit S protein, PsbS, was found to be necessary for energy-dependent quenching (qE), the major energy-dependent component of non-photochemical quenching (NPQ) in Arabidopsis thaliana. It is proposed that PsbS acts as a trigger of the conformational change that leads to the establishment of nonphotochemical quenching. However, the exact structure and function of PsbS in PSII are still unknown. Here, we clone and express the recombinant PsbS gene from Arabidopsis thaliana in E. coli and purify the resulting homogeneous protein. We used various biochemical and biophysical techniques to elucidate PsbS structure and function, including circular dichroism (CD), fluorescence, and DSC. The protein shows optimal stability at $4^{\circ}C$ and pH 7.5. The CD spectra of PsbS show that the conformational changes of the protein were strongly dependent on pH conditions. The CD curve for PsbS at pH 10.5 curve had the deepest negative peak and the peak of PsbS at pH 4.5 was the least negative. The fluorescence emission spectrum of the purified PsbS protein was also measured, and the ${\lambda}_{max}$ was found to be at 328 nm. PsbS revealed some structural changes under varying temperature and oxygen gas condition.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.43 no.1
• /
• pp.132-138
• /
• 2015

Trees, cultivated in containers, are appropriate in soil deformation such as road sites with cutting and filling. This study tested the effectiveness of trees produced in containers for early rootage in street tree transplantation. For the study, Korean Mountain Ashes(Sorbus alnifolia) were used for experimental groups. The groups were categorized into three categories: trees cultivated in containers with mulching treatment(group A), trees cultivated outdoors with mulching treatment (group B), and trees cultivated in containers with weeding treatment(group C). Each group consisted of ten trees of the same size and transplanted to the experimental site. In order to compare each group's rootage, the study was carried out with the chlorophyll fluorescence method by the analysis of photochemical reaction. As a result of the study, group B had the lowest the maximum fluorescence amount(P). The amount of fluorescence increased by OJ transition of the process, and appeared to reduce the photosystem II electron transport efficiency. In photosystem II, electron transfer energy flux through photosystem I(RE1o/RC, RE1o/CS) was also reduced by more than 20% in group B. These results may imply that transplantation of container-cultivated trees with mulching treatment provides the most rapid rootage among the groups. The weeding treatment is also more effective than mulching treatment for rapid rootage of street trees.

• Journal of Photoscience
• /
• v.9 no.2
• /
• pp.385-387
• /
• 2002

Direct EPR evidence of the photo-generation of superoxide radicals ( $O_2$$^{-.}$) was obtained by using spin trapping techniques in spinach photosystem II (PSII) membranes. $O_2$$^{-.}$ was detected by following the formation of 5-diethoxyphosphoryl-5-methyl-1 -pyrroline-N-oxide (DEPMPO) superoxide adducts, DEPMPO-OOH. The significant increase of the EPR signal amplitude of DEPMPO-OOH in N$H_2O$H-, CaC $l_2$- and NaCl-treated PSII membranes showed that the oxygen-evolving system has a close relation to the $O_2$$^{-.}$ production. PSII membranes with inactivated donor side could not prevent the $O_2$$^{-.}$ production efficiently. Treatments on PSII donor side also influence the maximum level and the kinetics of Chlorophyll (Chi) a fluorescence. Results suggested that manganese cluster and extrinsic proteins might affect Chi a fluorescence in ways different from that happens at the acceptor side of PSII.SII.SII.

• Rapid Communication in Photoscience
• /
• v.2 no.1
• /
• pp.18-23
• /
• 2013

The photosystem II (PSII) light harvesting complex (LHC) consists of a variety of pigment protein complexes which are involved in structural organization and regulation of photosynthetic unit. These LHC proteins encoded by a group of Lhcb genes are essential for the structural integrity of PSII supercomplex, the channeling the excitation energy to the reaction center of PSII and its redistribution to photosystem I by state transitions. Numerous studies with the help of recent technological advancements have enabled a significant progress in our understanding on the structure of PSII-LHCII supercomplexes and their mobilization under various light conditions. Here, we present a mini-review on the latest concepts and models depicting the structure of PSII-LHCII supercomplexes and the role of Lhcb proteins in their supra-molecular organization. Also we will review on the current understandings and remaining problems involved in the mobilization of the supercomplexes during state transitions and during high light illumination for controlling light energy distribution between the two photosystems.

• Journal of Environmental Science International
• /
• v.31 no.4
• /
• pp.311-318
• /
• 2022

In this study, we analyzed the relationships between weather factors and photosystem II activity (F_v/F_m), as a measure of photochemical efficiency, in three cool-season turfgrasses commonly planted on golf courses in Jeju, South Korea: perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), and creeping bentgrass (Agrostis palustris Huds.). In all three turfgrasses, F_v/F_m was higher during late summer than during early summer. However, in late summer, F_v/F_m was significantly lower in perennial ryegrass than in the other two species. In early summer, F_v/F_m in perennial ryegrass and Kentucky bluegrass was positively correlated with mean low temperature and extreme minimum temperature, whereas, in late summer, this parameter in Kentucky bluegrass and creeping bentgrass was positively correlated with relative humidity, and in creeping bentgrass was negatively correlated with mean high temperature, mean low temperature, and extreme maximum temperature. These results indicate that raising low temperatures is favorable for perennial ryegrass and Kentucky bluegrass in early summer, whereas, in late summer, the lowering of high temperatures proves to be beneficial for creeping bentgrass, and raising relative humidity is conducive to the growth of Kentucky bluegrass and creeping bentgrass. These findings will contribute to improving the selection and management of turfgrasses on golf courses and sports fields.

• Proceedings of the Botanical Society of Korea Conference
• /
• 1999.08a
• /
• pp.83-90
• /
• 1999

Electron crystallography of two-dimensional crystalsand electron cryo-microscopy is becoming an established method for determining the structure and function of a variety of membrane proteins that are providing difficult to crystallize in three dimension. In this study this technique has been used to investigate the structure of a ~160 kDa reaction centre sub-core complex of photosystem II. Photosystem II is a photosynthetic membrane protein consisting of more than 25 subunits. It uses solar energy to split water releasing molecular oxygen into the atmosphere and creates electrochemical potential across the thylakoid membrane, which is eventually utilized to generate ATP and NADPH. Images were taken using Philips CM200 field emission gun electron microscope with an acceleration voltage of 200kW at liquid nitrogen temperature. In total, 79 images recorded dat tilt angles ranging from 0 to 67 degree yielded amplitudes and phases for a three-dimensional map with an in-plant resolution of 6$\AA$ and 11.4$\AA$ in the third dimension shows at least 23 transmembrane helices resolved in a monomeric complex, of which 18 were able to be assigned to the D1, D2, CP47 , and cytochrome b559 alfa beta-subunits with their associated pigments that ae active in electron transport (Rhee, 1998, Ph.D.thesis). The D1/D2 heterodimer is located in the central position within the complex and its helical scalffold is remarkably similar to that of the reaction centres not only in purple bacteria but also in plant photosystem I (PSI) , indicating a common evoluationary origin of all types of reaction centre in photosynthetic organism known today 9RHee et al. 1998). The structural homology is now extended to the inner antenna subunit, ascribed to CP47 in our map, where the 6 transmembrane helices show a striking structural similarity to the corresponding helices of the PSI reaction centre proteins. The overall arrangement of the chlorophylls in the D1 /D2 heterodimer, and in particular the distance between the central pair, is ocnsistent with the weak exciton coupling of P680 that distinguishes this reaction centre from bacterial counterpart. The map in most progress towards high resolution structure will be presented and discussed.