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V V Klimov, S I Allakhverdiev, V G Ladygin
Photoreduction of Pheophytin 'a' (Pheo) accompanied by a decrease in the chlorophyll fluorescence yield is observed in photosystem II (PS II) of the whole cells of green algae Chlamydomonas reinhardii (a wild type and a mutant lacking both photosystem I and chlorophyll 'b'), Chlorella pyrenoidosa, Scenedesmus obliquus and cyanobacteria Phormidium laminosum, Anabaena variabilis and Cynechococcus elongatus under anaerobic conditions created by means of the glucose-glucoseoxidase-catalase. The photoreaction is activated by the addition of 1 μM CCCP, inhibited by 10 μM DCMU and reactivated upon subsequent addition of either ascorbate or dithionite...
January 1986: Photosynthesis Research
Pascal C Meunier, Derek S Bendall
Photosystem II cyclic electron transport was investigated at low pH in spinach thylakoids and PS II preparations from the cyanobacteriumPhormidium laminosum. Variable fluorescence (Fv) quenching at a very low light intensity was examined as an indicator of cyclic electron flow. A progressive quenching of Fv was observed as the pH was lowered; however, this was shown to be mainly due to an inhibition of oxygen evolution. Cyclic electron flow in the uninhibited centres was estimated to occur at a rate comparable to or smaller than 1 μ mole O2 mg Chl(-1) h(-1) in the pH range 5...
August 1993: Photosynthesis Research
B B Jørgensen, D C Nelson
The zonation and structure of phototrophic microbial mats were studied along two thermal gradients in sulfide-rich hot springs of southwest Iceland. The green, filamentous bacteriumChloroflexus and the unicellular, "high-temperature form" (HTF) ofMastigocladus formed mats growing up to a temperature limit of 62-66°C. The dominant phototrophs wereChloroflexus sp.,Mastigocladus laminosus, andPhormidium laminosum, respectively, at the three temperature intervals: >60°C, 60°C to 55-50°C, and <55-50°C...
September 1988: Microbial Ecology
Sandra Scanu, Johannes M Foerster, Monika Timmer, G Matthias Ullmann, Marcellus Ubbink
Recent studies on the electron transfer complex formed by cytochrome f and plastocyanin from Nostoc revealed that both hydrophobic and electrostatic interactions play a role in the process of complex formation. To study the balance between these two types of interactions in the encounter and the final state, the complex between plastocyanin from Phormidium laminosum and cytochrome f from Nostoc sp. PCC 7119 was investigated using NMR spectroscopy and Monte Carlo docking. Cytochrome f has a highly negative charge...
September 24, 2013: Biochemistry
Jody M Mason, Derek S Bendall, Christopher J Howe, Jonathan A R Worrall
Cytochrome c(6A) is a eukaryotic member of the Class I cytochrome c family possessing a high structural homology with photosynthetic cytochrome c(6) from cyanobacteria, but structurally and functionally distinct through the presence of a disulfide bond and a heme mid-point redox potential of +71mV (vs normal hydrogen electrode). The disulfide bond is part of a loop insertion peptide that forms a cap-like structure on top of the core α-helical fold. We have investigated the contribution of the disulfide bond to thermodynamic stability and (un)folding kinetics in cytochrome c(6A) from Arabidopsis thaliana by making comparison with a photosynthetic cytochrome c(6) from Phormidium laminosum and through a mutant in which the Cys residues have been replaced with Ser residues (C67/73S)...
February 2012: Biochimica et Biophysica Acta
Badri S Rajagopal, Michael T Wilson, Derek S Bendall, Christopher J Howe, Jonathan A R Worrall
The amino acid at position 51 in the cytochrome c(6) family is responsible for modulating over 100 mV of heme midpoint redox potential. As part of the present work, the X-ray structure of the imidazole adduct of the photosynthetic cytochrome c(6) Q51V variant from Phormidium laminosum has been determined. The structure reveals the axial Met ligand is dissociated from the heme iron but remains inside the heme pocket and the Ω-loop housing the Met ligand is stabilized through polar interactions with the imidazole and heme propionate-6...
April 2011: Journal of Biological Inorganic Chemistry: JBIC
Francisco J Muñoz-López, Simone Raugei, Miguel A De la Rosa, Antonio J Díaz-Quintana, Paolo Carloni
We report a theoretical investigation on the different stabilities of two plastocyanins. The first one belongs to the thermophilic cyanobacterium Phormidium laminosum and the second one belongs to its mesophilic relative Synechocystis sp. These proteins share the same topology and secondary-structure elements; however, the melting temperatures of their oxidised species differ by approximately 15 K. Long-time-scale molecular dynamics simulations, performed at different temperatures, show that the thermophilic protein optimises a set of intramolecular interactions (interstrand hydrogen bonding, salt bridging and hydrophobic clustering) within the region that comprises the strands beta 5 and beta 6, loop L5 and the helix...
March 2010: Journal of Biological Inorganic Chemistry: JBIC
Irene Díaz-Moreno, Francisco J Muñoz-López, Estrella Frutos-Beltrán, Miguel A De la Rosa, Antonio Díaz-Quintana
Many fleeting macromolecular interactions, like those being involved in electron transport, are essential in biology. However, little is known about the behaviour of the partners and their dynamics within their short-lived complex. To tackle such issue, we have performed molecular dynamics simulations on an electron transfer complex formed by plastocyanin and cytochrome f from the cyanobacterium Phormidium laminosum. Besides simulations of the isolated partners, two independent trajectories of the complex were calculated, starting from the two different conformations in the NMR ensemble...
November 2009: Bioelectrochemistry
Razif R Gabdoulline, Rebecca C Wade
The factors that determine the extent to which diffusion and thermal activation processes govern electron transfer (ET) between proteins are debated. The process of ET between plastocyanin (PC) and cytochrome f (CytF) from the cyanobacterium Phormidium laminosum was initially thought to be diffusion-controlled but later was found to be under activation control (Schlarb-Ridley, B. G.; et al. Biochemistry 2005, 44, 6232). Here we describe Brownian dynamics simulations of the diffusional association of PC and CytF, from which ET rates were computed using a detailed model of ET events that was applied to all of the generated protein configurations...
July 8, 2009: Journal of the American Chemical Society
Sachiko Yanagisawa, Peter B Crowley, Susan J Firbank, Anne T Lawler, David M Hunter, William McFarlane, Chan Li, Takamitsu Kohzuma, Mark J Banfield, Christopher Dennison
The influence of pi-interactions with a His ligand have been investigated in a family of copper-containing redox metalloproteins. The Met16Phe and Met16Trp pseudoazurin, and Leu12Phe spinach and Leu14Phe Phormidium laminosum plastocyanin variants possess active-site pi-contacts between the introduced residue and His81 and His87/92 respectively. The striking overlap of the side chain of Phe16 in the Met16Phe variant and that of Met16 in wild type pseudoazurin identifies that this position provides an important second coordination sphere interaction in both cases...
November 19, 2008: Journal of the American Chemical Society
Sarah E Hart, Christopher J Howe, Kenji Mizuguchi, Juan Fernandez-Recio
The interactions between redox proteins are transient in nature. Therefore, very few crystal structures are available for the complexes formed between these proteins. Computational docking simulations thus provide a useful alternative method for studying the interactions between electron transfer proteins. In this paper, we have studied the interactions between the aa(3)-type cytochrome c oxidase of the cyanobacterium Phormidium laminosum and its redox partners plastocyanin and cytochrome c(6) using a combination of comparative modelling techniques and docking simulations...
December 2008: Protein Engineering, Design & Selection: PEDS
Jonathan A R Worrall, Beatrix G Schlarb-Ridley, Torsten Reda, Maria J Marcaida, Robert J Moorlen, Juergen Wastl, Judy Hirst, Derek S Bendall, Ben F Luisi, Christopher J Howe
Cytochrome c6A is a unique dithio-cytochrome of green algae and plants. It has a very similar core structure to that of bacterial and algal cytochromes c6 but is unable to fulfill the same function of transferring electrons from cytochrome f to photosystem I. A key feature is that its heme midpoint potential is more than 200 mV below that of cytochrome c6 despite having His and Met as axial heme-iron ligands. To identify the molecular origins of the difference in potential, the structure of cytochrome c6 from the cyanobacterium Phormidium laminosum has been determined by X-ray crystallography and compared with the known structure of cytochrome c6A...
August 1, 2007: Journal of the American Chemical Society
A V Brianskaia, Z B Namsaraev, O M Kalashnikova, D D Barkhutova, B B Namsaraev, V M Gorlenko
The structure and production characteristics of microbial communities from the Urinskii alkaline hot spring (Buryat Republic, Russia) have been investigated. A distinctive characteristic of this hot spring is the lack of sulfide in the issuing water. The water temperature near the spring vents ranged from 69 to 38.5 degrees C and pH values ranged from 8.8 to 9.2. The total mineralization of water was less than 0.1 g/liter. Temperature has a profound effect on the species composition and biogeochemical processes occurring in the algal-bacterial mats of the Urinskii hot spring...
September 2006: Mikrobiologiia
Marta Llarena, María J Llama, Juan L Serra
A genomic region from the thermophilic, filamentous, nondiazotrophic cyanobacterium Phormidium laminosum including nrtC and nrtD was cloned and sequenced. These genes encode NrtC and NrtD, the ATP-binding subunits of the ABC bispecific transporter of nitrate/nitrite NRT. We report a different nrtC sequence from the one previously reported (Merchán et al., Plant Mol. Biol. 28:759-766, 1995) and we identified the presence of nrtD gene downstream nrtC in the nirA operon. Each gene was expressed in E. coli cells as a hexahistidine-tagged fusion protein...
December 2006: Biochimica et Biophysica Acta
Lars Schmidt, Hans E M Christensen, Pernille Harris
Plastocyanin from the cyanobacterium Anabaena variabilis was heterologously produced in Escherichia coli and purified. Plate-like crystals were obtained by crystallization in 1.15 M trisodium citrate and 7.67 mM sodium borate buffer pH 8.5. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 67.85, b = 45.81, c = 63.41 Angstrom. The structure of the oxidized protein was solved to a resolution of 1.6 Angstrom using plastocyanin from Phormidium laminosum as a search model...
September 2006: Acta Crystallographica. Section D, Biological Crystallography
L P Vernon, S Cardon
Vesicles prepared with the French press from membranes of cyanelles of Cyanophora paradoxa retain O(2) evolution activity with rates up to 500 micromoles 2,6-dichlorophenolindophenol reduced per hour per milligram chlorophyll. This activity is immediately lost when the vesicles are transferred from the sucrose-phosphate-citrate preparation buffer into dilute phosphate buffer. Similar preparations from Phormidium laminosum, a thermophilic cyanobacterium retain activity under such conditions. Photosystem I activities of both cyanobacterial vesicle preparations were determined by direct spectrophotometric measurement of N,N,N',N'-tetramethyl-p-phenylenediamine photooxidation in the presence of anthraquinone-2-sulfonate...
August 1982: Plant Physiology
Maria J Feio, Antonio Díaz-Quintana, José A Navarro, Miguel A De la Rosa
The thermal unfolding of plastocyanin from the mesophilic cyanobacterium Synechocystis is described herein, and the results are compared with those obtained for the homologous thermophilic protein from Phormidium laminosum. The thermal unfolding is irreversible under all the conditions that were investigated. Plastocyanin from the thermophilic organism, both in the native state and in the apoprotein form, proved to be more thermostable than its mesophilic counterpart under all experimental conditions. Synechocystis reduced plastocyanin has been shown to be more stable than the oxidized species, both with respect to the required temperature for protein unfolding and with respect to the kinetics of the process...
April 18, 2006: Biochemistry
R C Ford, A Holzenburg
Electron microscopy of monomeric and trimeric forms of the reaction centre of photosystem I from the thermophilic cyanobacterium Phormidium laminosum has allowed the construction of a three-dimensional model describing the shape of the complex. The trimeric form of the Photosystem I reaction centre complex was found to have a very regular shape corresponding to a rounded equilateral triangle with edges 18 nm long and a thickness of 6 nm. A distinctive chiral arrangement of the three reaction centres in the trimer could be observed on one face of the complex, whereas the opposing face appeared to be smooth with no distinctive internal features...
August 1988: EMBO Journal
R C Ford, D Picot, R M Garavito
The reaction centre of the photosynthetic membrane complex photosystem I (PSI) from the thermophilic cyanobacterium Phormidium laminosum was found to crystallize under a range of conditions. The crystallization method, which can occur in the presence of larger detergent molecules than those used previously for the crystallization of membrane proteins, is presented in this report. Several crystal forms have been observed, and some of these show birefringence and linear dichroism. Optical measurements on crystals thicker than 5 microm were severely restricted because of the very high chlorophyll density within the crystals, but linear dichroism measurements on thin single crystals were possible and the results are presented here...
June 1987: EMBO Journal
Daniel Nagore, Begoña Sanz, Javier Soria, Marta Llarena, María J Llama, Juan J Calvete, Juan L Serra
Most cyanobacteria take up nitrate or nitrite through a multisubunit ABC transporter (ATP-binding cassette) located in the cytoplasmic membrane. Nitrate and nitrite transport activity is instantaneously blocked by the presence of ammonium in the medium. Previous biochemical studies reported the existence of phosphorylation/dephosphorylation events of the nitrate transporter (NRT) related to the presence of ammonium-sensitive kinase/phosphatase activities in plasma membranes of the cyanobacterium Synechococcus elongatus PCC 6301...
February 2006: Biochimica et Biophysica Acta
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