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Vasily V Ptushenko, Tatiana V Zhigalova, Olga V Avercheva, Alexander N Tikhonov
In plants, the short-term regulation (STR, seconds to minute time scale) of photosynthetic apparatus is associated with the energy-dependent control in the chloroplast electron transport, the distribution of light energy between photosystems (PS) II and I, activation/deactivation of the Calvin-Benson cycle (CBC) enzymes, and relocation of chloroplasts within the plant cell. In this work, using a dual-PAM technique for measuring the time-courses of P700 photooxidation and Chl a fluorescence, we have investigated the STR events in Tradescantia fluminensis leaves...
March 7, 2018: Photosynthesis Research
Ido Caspy, Nathan Nelson
Plant photosystem I (PSI) is one of the most intricate membrane complexes in nature. It comprises two complexes, a reaction center and light-harvesting complex (LHC), which together form the PSI-LHC supercomplex. The crystal structure of plant PSI was solved with two distinct crystal forms. The first, crystallized at pH 6.5, exhibited P 21 symmetry; the second, crystallized at pH 8.5, exhibited P 212121 symmetry. The surfaces involved in binding plastocyanin and ferredoxin are identical in both forms. The crystal structure at 2...
February 27, 2018: Biochemical Society Transactions
William H J Wood, Craig MacGregor-Chatwin, Samuel F H Barnett, Guy E Mayneord, Xia Huang, Jamie K Hobbs, C Neil Hunter, Matthew P Johnson
Upon transition of plants from darkness to light the initiation of photosynthetic linear electron transfer (LET) from H2O to NADP+ precedes the activation of CO2 fixation, creating a lag period where cyclic electron transfer (CET) around photosystem I (PSI) has an important protective role. CET generates ΔpH without net reduced NADPH formation, preventing overreduction of PSI via regulation of the cytochrome b 6 f (cytb 6 f) complex and protecting PSII from overexcitation by inducing non-photochemical quenching...
February 2018: Nature Plants
Xin-Tong Zhou, Fang Wang, Yin-Ping Ma, Li-Jia Jia, Ning Liu, Hai-Yun Wang, Pan Zhao, Gui-Xian Xia, Nai-Qin Zhong
Accumulating evidence indicates that plant plastocyanin is involved in copper homeostasis, yet the physiological relevance remains elusive. In this study, we found that a plastocyanin gene (SsPETE2) from euhalophyte Suaeda salsa possessed a novel antioxidant function, which was associated with the copper-chelating activity of SsPETE2. In S. salsa, expression of SsPETE2 increased in response to oxidative stress and ectopic expression of SsPETE2 in Arabidopsis enhanced the antioxidant ability of the transgenic plants...
March 2018: Plant Science: An International Journal of Experimental Plant Biology
Hagai Raanan, Douglas H Pike, Eli K Moore, Paul G Falkowski, Vikas Nanda
Oxidoreductases catalyze electron transfer reactions that ultimately provide the energy for life. A limited set of ancestral protein-metal modules are presumably the building blocks that evolved into this diverse protein family. However, the identity of these modules and their path to modern oxidoreductases is unknown. Using a comparative structural analysis approach, we identify a set of fundamental electron transfer modules that have evolved to form the extant oxidoreductases. Using transition metal-containing cofactors as fiducial markers, it is possible to cluster cofactor microenvironments into as few as four major modules: bacterial ferredoxin, cytochrome c, symerythrin, and plastocyanin-type folds...
January 22, 2018: Proceedings of the National Academy of Sciences of the United States of America
Jiawei Pan, Dahui Huang, Zhonglong Guo, Zheng Kuang, He Zhang, Xinyu Xie, Zengfeng Ma, Shaopei Gao, Manuel T Lerdau, Chengcai Chu, Lei Li
The ability of a plant to produce grain, fruit, or forage depends ultimately on photosynthesis. There have been few attempts, however, to study microRNAs, which are a class of endogenous small RNAs post-transcriptionally programming gene expression, in relation to photosynthetic traits. We focused on miR408, one of the most conserved plant miRNAs, and overexpressed it in parallel in Arabidopsis, tobacco, and rice. The transgenic plants all exhibited increased copper content in the chloroplast, elevated abundance of plastocyanin, and an induction of photosynthetic genes...
January 13, 2018: Journal of Integrative Plant Biology
Shengjie Liu, Jiadong Gao, Zhongjian Chen, Xiaoyan Qiao, Hualin Huang, Baiyuan Cui, Qingfeng Zhu, Zhangyan Dai, Hualing Wu, Yayan Pan, Chengwei Yang, Jun Liu
BACKGROUND: A recently discovered tea [Camellia sinensis (L.) O. Kuntze] cultivar can generate tender shoots in winter. We performed comparative proteomics to analyze the differentially accumulated proteins between winter and spring tender shoots of this clonal cultivar to reveal the physiological basis of its evergrowing character during winter. RESULTS: We extracted proteins from the winter and spring tender shoots (newly formed two leaves and a bud) of the evergrowing tea cultivar "Dongcha11" respectively...
November 20, 2017: BMC Plant Biology
Mingpu Tan, Dan Cheng, Yuening Yang, Guoqiang Zhang, Mengjie Qin, Jun Chen, Yahua Chen, Mingyi Jiang
BACKGROUND: The migration of cadmium (Cd) from contaminated soil to rice is a cause for concern. However, the molecular mechanism underlying the response of rice roots to various Cd stresses remains to be clarified from the viewpoint of the co-expression network at a system-wide scale. RESULTS: We employed a comparative RNAseq-based approach to identify early Cd-responsive differentially expressed genes (DEGs) in rice 'Nipponbare' seedling roots after 1 h of high-Cd treatment...
November 7, 2017: BMC Plant Biology
Agu Laisk, Vello Oja
The OJDIP rise in chlorophyll fluorescence during induction at different light intensities was mathematically modeled using 24 master equations describing electron transport through photosystem II (PSII) plus ordinary differential equations for electron budgets in plastoquinone, cytochrome f, plastocyanin, photosystem I, and ferredoxin. A novel feature of the model is consideration of electron in- and outflow budgets resulting in changes in redox states of Tyrosine Z, P680, and QA as sole bases for changes in fluorescence yield during the transient...
September 21, 2017: Photosynthesis Research
Jin-Ping Zhang, Yang Yu, Yan-Zhao Feng, Yan-Fei Zhou, Fan Zhang, Yu-Wei Yang, Meng-Qi Lei, Yu-Chan Zhang, Yue-Qin Chen
Increasing grain yield is the most important object of crop breeding. Here, we report that the elevated expression of a conserved microRNA, OsmiR408, could positively regulate grain yield in rice (Oryza sativa) by increasing panicle branches and grain number. We further showed that OsmiR408 regulates grain yield by down-regulating its downstream target, OsUCL8, which is an uclacyanin (UCL) gene of the phytocyanin family. The knock down or knock out of OsUCL8 also increases grain yield, while the overexpression of OsUCL8 results in an opposite phenotype...
November 2017: Plant Physiology
Anna A Hippmann, Nina Schuback, Kyung-Mee Moon, John P McCrow, Andrew E Allen, Leonard J Foster, Beverley R Green, Maria T Maldonado
There is an intricate interaction between iron (Fe) and copper (Cu) physiology in diatoms. However, strategies to cope with low Cu are largely unknown. This study unveils the comprehensive restructuring of the photosynthetic apparatus in the diatom Thalassiosira oceanica (CCMP1003) in response to low Cu, at the physiological and proteomic level. The restructuring results in a shift from light harvesting for photochemistry-and ultimately for carbon fixation-to photoprotection, reducing carbon fixation and oxygen evolution...
2017: PloS One
Ulrich Schreiber
Properties and performance of the recently introduced Dual/KLAS-NIR spectrophotometer for simultaneous measurements of ferredoxin (Fd), P700, and plastocyanin (PC) redox changes, together with whole leaf chlorophyll a (Chl) fluorescence (emission >760, 540 nm excitation) are outlined. Spectral information on in vivo Fd, P700, and PC in the near-infrared region (NIR, 780-1000 nm) is presented, on which the new approach is based. Examples of application focus on dark-light and light-dark transitions, where maximal redox changes of Fd occur...
December 2017: Photosynthesis Research
Daria V Dibrova, Daria N Shalaeva, Michael Y Galperin, Armen Y Mulkidjanian
The cytochrome bc (cyt bc) complexes are involved in Q-cycling; they oxidize membrane quinols by high-potential electron acceptors, such as cytochromes or plastocyanin, and generate transmembrane proton gradient. In several prokaryotic lineages, and also in plant chloroplasts, the catalytic core of the cyt bc complexes is built of a four-helical cytochrome b (cyt b) that contains three hemes, a three-helical subunit IV, and an iron-sulfur Rieske protein (cytochrome b6 f-type complexes). In other prokaryotic lineages, and also in mitochondria, the cyt b subunit is fused with subunit IV, yielding a seven- or eight-helical cyt b with only two hemes (cyt bc1 -type complexes)...
September 2017: Physiologia Plantarum
Amanda L Le Sueur, Sashary Ramos, Jonathan D Ellefsen, Silas Cook, Megan C Thielges
Two-dimensional infrared (2D IR) spectroscopy provides a powerful approach for the direct study of molecular dynamics with high spatial and temporal resolution. Its application for investigating specific locations in proteins requires the incorporation of IR probe groups with spectrally isolated absorptions to avoid the congestion inherent to protein spectra. This has motivated extensive efforts toward the development of new IR probes, but there remains a need for those that can extend the experimental time range, which is limited by their vibrational lifetimes...
April 26, 2017: Analytical Chemistry
Ilya B Kovalenko, Olga S Knyazeva, Taras K Antal, Vladimir Y Ponomarev, Galina Yu Riznichenko, Andrei B Rubin
A model of electron transport from cytochrome f to photosystem I mediated by plastocyanin was designed on the basis of the multiparticle Brownian dynamics method. The model combines events which occur over a wide time range, including protein diffusion along the thylakoid membrane, long-distance interactions between proteins, formation of a multiprotein complex, electron transfer within a complex and complex dissociation. Results of the modeling were compared with the experimental kinetics measured in chloroplast thylakoids...
September 2017: Physiologia Plantarum
Alexander N Tikhonov, Alexey V Vershubskii
In chloroplasts, photosynthetic electron transport complexes interact with each other via the mobile electron carriers (plastoquinone and plastocyanin) which are in surplus amounts with respect to photosystem I and photosystem II (PSI and PSII), and the cytochrome b 6 f complex. In this work, we analyze experimental data on the light-induced redox transients of photoreaction center P700 in chloroplasts within the framework of our mathematical model. This analysis suggests that during the action of a strong actinic light, even significant attenuation of PSII [for instance, in the result of inhibition of a part of PSII complexes by DCMU or due to non-photochemical quenching (NPQ)] will not cause drastic shortage of electron flow through PSI...
September 2017: Photosynthesis Research
Harry B Gray, Jay R Winkler
Prior to 1950, the consensus was that biological transformations occurred in two-electron steps, thereby avoiding the generation of free radicals. Dramatic advances in spectroscopy, biochemistry, and molecular biology have led to the realization that protein-based radicals participate in a vast array of vital biological mechanisms. Redox processes involving high-potential intermediates formed in reactions with O2 are particularly susceptible to radical formation. Clusters of tyrosine (Tyr) and tryptophan (Trp) residues have been found in many O2-reactive enzymes, raising the possibility that they play an antioxidant protective role...
October 2016: Israel Journal of Chemistry
Jemaa Essemine, Yi Xiao, Mingnan Qu, Hualing Mi, Xin-Guang Zhu
Previously we have shown that a quick down-regulation in PSI activity compares to that of PSII following short-term heat stress for two rice groups including C4023 and Q4149, studied herein. These accessions were identified to have different natural capacities in driving cyclic electron flow (CEF) around PSI; i.e., low CEF (lcef) and high CEF (hcef) for C4023 and Q4149, respectively. The aim of this study was to investigate whether these two lines have different mechanisms of protecting photosystem II from photodamage under heat stress...
April 2017: Journal of Plant Physiology
Catherine A Hurd, Nicholas A Besley, David Robinson
Plastocyanin is a copper containing protein that is involved in the electron transfer process in photosynthetic organisms. The active site of plastocyanin is described as an entatic state whereby its structure represents a compromise between the structures favored by the oxidized and reduced forms. In this study, the nature of the entatic state is investigated through density functional theory-based hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations. The strain energy is computed to be 12...
June 15, 2017: Journal of Computational Chemistry
Hubert Mayerhofer, Emeline Sautron, Norbert Rolland, Patrice Catty, Daphné Seigneurin-Berny, Eva Pebay-Peyroula, Stéphanie Ravaud
Copper is a crucial ion in cells, but needs to be closely controlled due to its toxic potential and ability to catalyse the formation of radicals. In chloroplasts, an important step for the proper functioning of the photosynthetic electron transfer chain is the delivery of copper to plastocyanin in the thylakoid lumen. The main route for copper transport to the thylakoid lumen is driven by two PIB-type ATPases, Heavy Metal ATPase 6 (HMA6) and HMA8, located in the inner membrane of the chloroplast envelope and in the thylakoid membrane, respectively...
2016: PloS One
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