Primary Processes Of Photosynthesis Research Articles

Structural and preliminary molecular dynamics studies of the Rhodobacter sphaeroides reaction center and its mutant form L(M196)H + H(M202)L

Pigment-protein interactions are responsible for the high efficiency of the light-energy transfer and conversion in photosynthesis. The reaction center (RC) from the purple bacterium Rhodobacter sphaeroides is the most convenient model for studying the mechanisms of primary processes of photosynthesis. Site-directed mutagenesis can be used to study the effect of the protein environment of electron-transfer cofactors on the optical properties, stability, pigment composition, and functional activity of RC. The preliminary analysis of RC was performed by computer simulation of the amino acid substitutions L(M196)H + H(M202)L at the pigment-protein interface and by estimating the stability of the threedimensional structure of the mutant RC by the molecular dynamics method. The doubly mutated reaction center was overexpressed, purified, and crystallized. The three-dimensional structure of this mutant was determined by X-ray crystallography and compared with the molecular dynamics model.

Diurnal changes in photosynthetic activity of the biological soil crust and lichen: Effects of abiotic factors (Petuniabukta, Svalbard)

In polar ecosystems, primary producers have to cope with a very harsh climate that limits the time available for growth and biomass production. In this study, diurnal measurement of photosynthetic processes in biological soil crust and a lichen were carried out in Petuniabukta, Spitsbergen. For field measurements, a method of induced fluorescence of chlorophyll was used. Measurements of photosynthetic activity were taken as repetitive measurements of effective quantum yield of photosystem II (ΦPSII). The short-term field measurements were carried out for 10 days in summer 2014. ΦPSII was recorded each 5 minutes as well as microclimatic data (air temperature, air humidi-ty, photosynthetically active radiation - PAR). The microclimatic parameters were recorded by a datalogger. In general, physiological activity of both biological soil crust and a lichen showed daily courses. Tested lichen was Cladonia rangiferina and the most dominant species in biological soil crust was Nostoc sp. Typically, most of ΦPSII values ranged 0.6 – 0.7 in both model organisms. The results have shown that photosynthetic activity was strongly correlated with all observed abiotic factors in both study objects. Particularly important was the relation found between PAR and ΦPSII in biological soil crust. When the biological soil crust was exposed to high PAR doses of irradiation (about 2300 µmol m-2 s-1) photoinhibition of primary processes of photosynthesis was observed as ΦPSII decrease, while photosynthetic activity of lichen remained at same level. Furthermore, it has been demonstrated increasing that in situ photosynthetic activity increased in both biological soil crust and lichen with a decrease in temperature.

Effect of temperature and increased concentration of CO2 on growth and photosynthetic activity of polar alga Trebouxia sp.

Trebouxia sp., a lichen symbiotic alga, was isolated from lichen Usnea antarctica collected at James Ross Island, Antarctica. After isolation, the alga was cultivated on Bold‘s Basal Medium (BBM-agar) with addition of nitrogen for 12 days. Growth of alga and its photosynthetic properties were studied in relation to increased concentration of CO2 (850±50 ppm) and two cultivation temperature (8 and 12°C). Physiological status of algae was evaluated by chlorophyll fluorescence parameters. Simultaneously, content of pigments and changes in biomass were evaluated during cultivation period. Evaluation of physiological state of Trebouxia sp. was carried out after the end of experiment. Results of chlorophyll fluorescence induction parameters and content of pigments showed that the highest efficiency of primary processes of photosynthesis was found at the treatment with elevated concentration of CO2 and temperature 12°C. In this treatment, potential quantum yield of photochemical processes in photosystem II (FV/FM) was 0.44 and content of Chl a was 5.14 µg ml-1. In contrast, the lowest efficiency of primary processes was found at the treatment with addition of CO2 and temperature 8°C, where value of FV/FM reached 0.37 and content of Chl a was 3.71 µg ml-1.

George Feher: a pioneer in reaction center research

Our understanding of photosynthesis has been greatly advanced by the elucidation of the structure and function of the reaction center (RC), the membrane protein responsible for the initial light-induced charge separation in photosynthetic bacteria and green plants. Although today we know a great deal about the details of the primary processes in photosynthesis, little was known in the early days. George Feher made pioneering contributions to photosynthesis research in characterizing RCs from photosynthetic bacteria following the ground-breaking work of Lou Duysens and Rod Clayton (see articles in this issue by van Gorkom and Wraight). The work in his laboratory at the University of California, San Diego, started in the late 1960s and continued for over 30 years. He isolated a pure RC protein and used magnetic resonance spectroscopy to study the primary reactants. Following this pioneering work, Feher studied the detailed structure of the RC and the basic electron and proton transfer functions that it performs using a wide variety of biophysical and biochemical techniques. These studies, together with work from many other researchers, have led to our present detailed understanding of these proteins and their function in photosynthesis. The present article is a brief historical account of his pioneering contributions to photosynthesis research. A more detailed description of his work can be found in an earlier biographical paper (Feher in Photosynth Res 55:1-40, 1998a).

Thermoluminescence and conformational transitions in the primary processes of photosynthesis

Thermoluminescence and conformational transitions in the primary processes of photosynthesis

Thermoluminescence in the primary processes of photosynthesis. “New” approaches to numerical simulation

Thermoluminescence in the primary processes of photosynthesis. “New” approaches to numerical simulation

Molecular Mechanism of Solar Energy Harvesting by Purple Photosynthetic Bacteria*

Photosynthesis is arguably the most important biological process,by it organisms harvest solar energy and transfer it into chemical energy for growth and reproduction.The photosynthetic bacteria are the earliest microbe with photosynthesis found on earth.The photosynthetic apparatus of purple bacteria is a nanometric assembly in the intracytoplasmic membranes and consists of pigment-protein complexes,the photosynthetic RC(Reaction center) and LH(Light harvesting).The primary processes of photosynthesis involve absorption of photons by LH complexes,transfer of excitation energy from the LH complexes to the photosynthetic RC,where the primary energy conversion takes place.The researches on molecular structure and mechanism of purple photosynthetic bacteria harvesting solar energy were summarized.Molecular biology techniques and spectroscopic analysis were applied to research the expression and function of puc2BA and pucsBA by the authors,and it was concluded that the puc2BA gene was normally expressed in Rhodobacter sphaeroides,the pucsBA gene of Rhodovulum sulfidophilum and the pufBA gene of R.sphaeroides were expressed in R.sphaeroides,and the heterologous LHII and native LHI were produced and assembled in the membrane.

A tribute to Seymour Steven Brody: in memoriam (November 29, 1927 to May 25, 2010)

We honor Steve Brody, a dear friend and a mentor on what would have been his 83rd birthday (November 29, 2010). Steve was a pioneer of chlorophyll structure and function, an outstanding biophysicist, an innovator, an artist and an adventurer, a true renaissance man. We present here first his first-of-a-kind contributions on the primary processes of photosynthesis at the University of Illinois at Urbana-Champaign, and then review his research on the interactions of chlorophyll monolayers and various photosynthetic electron donors and acceptors in artificial membrane systems at New York University. We highlight significant research contributions of interest to the reader and conclude with biographical notes.

ChemInform Abstract: Primary Processes in Photosynthesis: What Do we Learn from High-Field EPR Spectroscopy?

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Gernot Renger (ed): Primary processes of photosynthesis: principles and apparatus, parts 1 and 2

Gernot Renger (ed): Primary processes of photosynthesis: principles and apparatus, parts 1 and 2

Assessment of the effects of methylmercury and copper ions on primary processes of photosynthesis in green microalga Chlamydomonas moewusii by analysis of the kinetic curves of variable chlorophyll fluorescence

The effect of methylmercury and copper ions on the kinetics of light induction and dark relaxation of the variable fluorescence of chlorophyll a has been studied on cultures of unicellular alga Chlamydomonas moewusii. Methylmercury was effective at much lower levels. The toxicants at concentrations that did not decrease the photochemical activity of PS II (Fv/Fm) did affect the electron transport on the acceptor side of PS II, nonphotochemical quenching of excitation in the antenna, and reoxidation of the quinone pool. Our results indicate that this approach can be used for detecting the changes in plant cells at the early stages of toxicant action.

Revealing The Linear Aggregates Of Light Harvesting Antenna Proteins In Photosynthetic Membranes

How light energy is harvested in a natural photosynthetic membrane through energy transfer is closely related to the stoichiometry and arrangement of light harvesting antenna proteins in the membrane. Their specific architecture helps them to absorb photons in the primary process of photosynthesis that is subsequently followed by a rapid and efficient energy transfer among the light harvesting proteins (LH2 and LH1) and to the reaction center. In this work, using atomic force microscopy (AFM) imaging, single membrane fragment FRET spectroscopy, spectral fluctuation analysis, and time-resolved spectroscopic analysis, we show the identification of linear aggregates of light harvesting proteins, LH2, in the photosynthetic membranes under ambient conditions. Our results suggest that the light harvesting proteins, LH2, mostly exist in two states, the aggregated and non-aggregated states in the photosynthetic membranes. Our results shed a light on understanding the complex intramolecular energy transfer dynamics and mechanism of the light harvesting in the photosynthetic membranes.

Book Review of Primary Processes of Photosynthesis: Principles and Apparatus, Parts 1−2

Book Review of Primary Processes of Photosynthesis: Principles and Apparatus, Parts 1−2

Primary Processes of Photosynthesis. Principles and Apparatus. 2 Vols. Edited by Gernot Renger.

Primary Processes of Photosynthesis. Principles and Apparatus. 2 Vols. Edited by Gernot Renger.

Chlorophyll fluorescence as an indicator of fluoranthene phototoxicity

The effect of the short-time exposure (12, 24 and 48 h) of increasing concentration (0.1, 1 and 10 mg/l) of intact (FLT) and photo-modified (phFLT) fluoranthene on the chlorophyll fluorescence parameters (<i>F</i><sub>0</sub>, <i>F</i><sub>V</sub>/<i>F</i><sub>M</sub> and Φ<sub>II</sub>) in pea plants (<i>Pisum sativum</i> L. cv. Lantra) was investigated. Plants took up both forms of fluoranthene by two different ways, via roots or via leaves. The obtained results demonstrated a significant increase in <i>F</i><sub>0</sub> and decrease in <i>F</i><sub>V</sub>/<i>F</i><sub>M</sub> and Φ<sub>II</sub> in plants treated by 1 and 10 mg/l FLT and phFLT. An earlier response to presence of FLT and phFLT in the environment was demonstrated by application on cut leaves. The primary processes of photosynthesis were not significantly influenced by short-time phFLT treatment.

Dual Luminescence and Long-Lived Charge-Separated States in Donor-Acceptor Assemblies Based on Tetrathiafulvalene-Fused Ruthenium(II)-Polypyridine Complexes

The creation of long-lived charge-separated states in donor–acceptor assemblies has been the goal of many studies aimed at mimicking the primary processes in photosynthesis. Here we present such assemblies based on tetrathiafulvalene (TTF) as electron donor and a dipyridophenazine (dppz) unit as electron acceptor in the form of a fused ligand (TTF-dppz) coordinated to ruthenium(II) via the dipyrido coordination site and with 2,2?-bipyridine (bpy) as auxiliary ligand, namely [Ru(bpy)3?x(TTF-dppz)x]2+ (x = 1?3). For x = 2, irradiation into the metal to dppz charge transfer transition results in electron transfer from TTF to ruthenium, thus creating a charge-separated state best described by [(TTF+-dppz)Ru(dppz?-TTF)(bpy)]2+ with a lifetime of 2.5 ?s in dichloromethane.

Photoinduced toxicity of fluoranthene on primary processes of photosynthesis in lichens

The effect of increasing concentrations (0·01, 0·1, 1 and 5 mg l−1) of intact (FLT) and photo-modified (phFLT) fluoranthene and the duration of exposure (1, 2, 3, 5 and 7 days) on the chlorophyll fluorescence parameters (F0, FV/FM, and ΦII) of symbiotic algae in the thalli of two foliose lichens Lasallia pustulata and Umbilicaria hirsuta was investigated. In addition the FLT concentration in thalli of both lichen species was determined and a bioconcentration factor (BCF) was calculated. The results obtained demonstrated that the concentrations of FLT and especially phFLT (1 and 5 mg l−1) applied affected primary photochemical processes of photosynthesis in the algae of both lichen species. The F0 value increased and the FV/FM and ΦII values decreased. The fluoranthene content in the thallus of both lichen species increased with increasing FLT concentration in the environment.

Curling during desiccation protects the foliose lichen Lobaria pulmonaria against photoinhibition

This study aims to assess the photoprotective potential of desiccation-induced curling in the light-susceptible old forest lichen Lobaria pulmonaria by using chlorophyll fluorescence imaging. Naturally curled thalli showed less photoinhibition-induced limitations in primary processes of photosynthesis than artificially flattened specimens during exposures to 450 micromol m-2 s-1 in the laboratory after both 12- (medium dose treatment) and 62-h duration (high dose treatment). Thallus areas shaded by curled lobes during light exposure showed unchanged values of measured chlorophyll fluorescence parameters (FV/FM, PhiPS II), whereas non-shaded parts of curled thalli, as well as the mean for the entire flattened thalli, showed photoinhibitory limitation after light treatments. Furthermore, the chlorophyll fluorescence imaging showed that the typical small-scale reticulated ridges on the upper side of L. pulmonaria caused a spatial, small-scale reduction in damage due to minor shading. Severe dry-state photoinhibition readily occurred in flattened and light-treated L. pulmonaria, although the mechanisms for such damage in a desiccated and inactive stage are not well known. Natural curling is one strategy to reduce the chance for serious photoinhibition in desiccated L. pulmonaria thalli during high light exposures.

A single chlorophyll in each of the core antennas CP43 and CP47 transferring excitation energies to the reaction center in Photosystem II of photosynthesis

Trapping of pigment excitation energies in the core antenna by the reaction center (RC) in Photosystem II (PS II) is a process rate-limiting in the whole primary processes of photosynthesis until initial excitation-energy fixation by charge separation in the RC. It takes place from a single chlorophyll (Chl) in each of transmembrane protein–pigment complexes CP43 and CP47, which compose the core antenna separately attached to each of the two pigment strands 1 and 2 in the RC, respectively. Its excitation energies are transferred to the accessory Chl (B) or the adjacent pheophytin (H) in each of the strands. These features unique in PS II can be rationalized to have arisen as a byproduct of the requirement that the oxidized state P + of the central Chl pair P in the RC must have an exceptionally high redox potential for extracting an electron from water only in PS II. These features were clarified by reproducing the observed rate constant of excitation-energy trapping by the RC from the core antenna. Playing important roles here is the excitation spectrum of each pigment in the RC obtained by analyzing the absorption spectrum of the RC [K. Saito, K. Mukai, H. Sumi, Chem. Phys. Lett. 401 (2005) 122], on the basis of the observed pigment-energy arrangement therein. Here, the excited state B * of B is lowest in the RC with H * locating a little (∼40 cm −1) higher, while P * is considerably (∼180 cm −1) higher in association with the very high redox potential of P +, although only P carries an exciton as P * on this Chl dimer in the RC.

Meet the Guest Editor

Joachim Vater obtained his diploma (1965) and his Doctors degrees (Dr. rer. nat., 1972) from the Technical University Berlin working under the supervision of Professor Dr. H. T. Witt at the Max-Volmer-Institute in the field of primary processes in photosynthesis of higher plants. From 1972 - 1976 he was research assistant (postdoc) of Professor Dr. H. Kleinkauf at the Institute of Biochemistry and Molecular Biology of the Technical University Berlin in the field of nonribosomal biosynthesis of bioactive peptides. Since 1976 he is a research associate at this institute. He was the leader of numerous research projects on the biosynthesis and biotechnological utilization of bioactive peptides. From 1994-1998 he was the coordinator of interdisciplinary research projects on microbial cell factories in Biotechnology programmes of the European Commission. His interests include: Nonribosomal peptide biosynthesis; peptide synthetases; lipopeptides; surfactin; antibiotic and antiviral agents; combinatorial biosynthesis of peptides; peptide design; biotechnological exploitation of bioactive peptides; functional genomics of microbial secondary metabolites; metabolite screening; advanced mass spectrometric methodology for analysis of conplex biological samples (whole cells, subcellular particles, organelles, cellular extracts); protein chemistry; surface chemistry. SELECTED PUBLICATIONS Stein, T.; Vater. J.; Kruft, V.; Otto, A.; Wittmann-Liebold, B.; Franke, P.; Panico, M.; McDowell, R.; Morris, H.R. The multiple carrier model of nonribosomal peptide biosynthesis at modular multienzymatic templates. J. Biol. Chem. 1996, 271, 15428-15435. Vollenbroich, D.; Pauli, G.; Özel, M.; Vater, J. Antimycoplasma properties and application in cell culture of surfactin, a lipopeptide antibiotic from Bacillus subtilis. Appl. Environ. Microbiol. 1997, 63, 44-49. Vollenbroich, D.; Ozel, M.; Vater, J.; Kamp, R.M.; Pauli, G. Mechanism of inactivation of enveloped viruses by the biosurfactant surfactin from Bacillus subtilis. Biologicals 1997, 25, 289-297. Duitman, E.H.; Hamoen, L.W.; Rembold, M.; Venema, G.; Seitz, H.; Saenger, W.; Bernhard, W.; Reinhardt, R.; Schmidt, M.; Ullrich, C.; Stein, T.; Leenders, F.; Vater, J. The mycosubtilin synthetase of Bacillus subtilis ATCC6633: A multifunctional hybrid between a peptide synthetase, an aminotransferase, and a fatty acid synthase. Proc. Natl. Acad. Sci. USA 1999, 96, 13294-13299. Leenders, F.; Stein, T.H.; Kablitz, B.; Franke, P.; Vater, J. Rapid typing of Bacillus subtilis strains by their secondary metabolites using matrix-assisted laser desorption / ionization mass spectrometry of intact cells. Rapid Commun. Mass Spectrom. 1999, 13, 943-949. Vater, J.; Kablitz, B.; Wilde, C.; Franke, P.; Mehta, N.; Cameotra, S.S. Matrix-assisted laser desorption ionization-time of flight mass spectrometry of lipopeptide biosurfactants in whole cells and culture filtrates of Bacillus subtilis C-1 isolated from petroleum sludge. Appl. Environ. Microbiol. 2002, 68, 6210-6219.