| an early origin of plastids within the cyanobacterial divergence is suggested by evolutionary trees based on complete 16s rrna sequences. | it is generally accepted that the plastids arose from a cyanobacterial ancestor, but the exact phylogenetic relationships between cyanobacteria and plastids are still controversial. most studies based on partial 16s rrna sequences suggested a relatively late origin of plastids within the cyanobacterial divergence. in order to clarify the exact relationship and divergence order of cyanobacteria and plastids, we studied their phylogeny on the basis of nearly complete 16s rrna gene sequences. the d ... | 1995 | 8524048 |
| glyceraldehyde-3-phosphate dehydrogenase gene diversity in eubacteria and eukaryotes: evidence for intra- and inter-kingdom gene transfer. | cyanobacteria contain up to three highly divergent glyceraldehyde-3-phosphate dehydrogenase (gapdh) genes: gap1, gap2, and gap3. genes gap1 and gap2 are closely related at the sequence level to the nuclear genes encoding cytosolic and chloroplast gapdh of higher plants and have recently been shown to play distinct key roles in catabolic and anabolic carbon flow, respectively, of the unicellular cyanobacterium synechocystis sp. pcc6803. in the present study, sequences of 10 gapdh genes distribute ... | 1999 | 10331270 |
| proton gradients in intact cyanobacteria. | the internal ph values of two unicellular cyanobacterial strains were determined with electron spin resonance probes, over an external ph range of 6 to 9, in the light and in the dark. the slow growing, thylakoid-lacking gloeobacter violaceus was found to have a low capacity for maintaining a constant internal ph. the distribution pattern of weak acid and amine nitroxide spin probes across the cell membranes of this organism, in the light and in the dark, was consistent with the assumption tha ... | 1987 | 11539679 |
| nonribosomal peptide synthetase genes occur in most cyanobacterial genera as evidenced by their distribution in axenic strains of the pcc. | previous studies largely carried out with environmental samples or axenic and non-axenic cultures suggested that cyanobacteria may be a rich source of hitherto unexplored bioactive compounds. this has been confirmed in the present study by a screening of 146 axenic strains from the pasteur culture collection (pcc) of cyanobacteria. use of degenerate pcr primers, designed on the basis of conserved sequence motifs in the aminoacyl-adenylation domain of peptide synthetases, revealed the presence of ... | 2001 | 11734889 |
| genetic tools for cyanobacteria. | cyanobacteria are oxygenic photosynthetic bacteria that have been used increasingly to study diverse biological processes, including photosynthesis and its regulation; cell differentiation and n2 fixation; metabolism of nitrogen, carbon, and hydrogen; resistance to environmental stresses; and molecular evolution. many vectors and other genetic tools have been developed for unicellular and filamentous strains of cyanobacteria. transformation, electroporation, and conjugation are used for gene tra ... | 2002 | 11876404 |
| unique fluorescence properties of a cyanobacterium gloeobacter violaceus pcc 7421: reasons for absence of the long-wavelength psi chl a fluorescence at -196 degrees c. | we investigated the reason for the absence of the long-wavelength psi chl a fluorescence at -196 degrees c in the cyanobacterium gloeobacter violaceus using two methods: p-nitrothiophenol (p-ntp) treatment and time-resolved fluorescence spectra. the p-ntp treatment showed that psii chl a fluorescence was specifically affected in a manner similar to that for synechocystis sp. pcc 6803 and spinach chloroplasts, although there were no components modified by the p-ntp treatment, indicating an absenc ... | 2002 | 12091711 |
| complete genome structure of gloeobacter violaceus pcc 7421, a cyanobacterium that lacks thylakoids. | the nucleotide sequence of the entire genome of a cyanobacterium gloeobacter violaceus pcc 7421 was determined. the genome of g. violaceus was a single circular chromosome 4,659,019 bp long with an average gc content of 62%. no plasmid was detected. the chromosome comprises 4430 potential protein-encoding genes, one set of rrna genes, 45 trna genes representing 44 trna species and genes for tmrna, b subunit of rnase p, srp rna and 6sa rna. forty-one percent of the potential protein-encoding gene ... | 2003 | 14621292 |
| complete genome structure of gloeobacter violaceus pcc 7421, a cyanobacterium that lacks thylakoids (supplement). | | 2003 | 14621296 |
| unique constitution of photosystem i with a novel subunit in the cyanobacterium gloeobacter violaceus pcc 7421. | constitution of the photosystem i complex isolated from the cyanobacterium gloeobacter violaceus pcc 7421 was investigated by tricine-urea-sds-page, followed by peptide mass fingerprinting or n-terminal sequencing. eight subunits (psaa, psab, psac, psad, psae, psaf, psal and psam) were identified as predicted from the genome sequence. a novel subunit (psaz) was discovered, but psai, psaj, psak and psax were absent. psab has a c-terminal extension with 155 amino acids in addition to the conserved ... | 2004 | 15589832 |
| identification of a new family of putative pd-(d/e)xk nucleases with unusual phylogenomic distribution and a new type of the active site. | prediction of structure and function for uncharacterized protein families by identification of evolutionary links to characterized families and known structures is one of the cornerstones of genomics. theoretical assignment of three-dimensional folds and prediction of protein function even at a very general level can facilitate the experimental determination of the molecular mechanism of action and the role that members of a given protein family fulfill in the cell. here, we predict the three-di ... | 2005 | 15720711 |
| the cyanobacterium gloeobacter violaceus pcc 7421 uses bacterial-type phytoene desaturase in carotenoid biosynthesis. | carotenoid composition and its biosynthetic pathway in the cyanobacterium gloeobacter violaceus pcc 7421 were investigated. beta-carotene and (2s,2's)-oscillol 2,2'-di(alpha-l-fucoside), and echinenone were major and minor carotenoids, respectively. we identified two unique genes for carotenoid biosynthesis using in vivo functional complementation experiments. in gloeobacter, a bacterial-type phytoene desaturase (crti), rather than plant-type desaturases (crtp and crtq), produced lycopene. this ... | 2005 | 15811329 |
| the secondary electron acceptor of photosystem i in gloeobacter violaceus pcc 7421 is menaquinone-4 that is synthesized by a unique but unknown pathway. | the secondary electron acceptor of photosystem (ps) i in the cyanobacterium gloeobacter violaceus pcc 7421 was identified as menaquinone-4 (mq-4) by comparing high performance liquid chromatograms and absorption spectra with an authentic compound. the mq-4 content was estimated to be two molecules per one molecule of chlorophyll (chl) a', a constituent of p700. comparative genomic analyses showed that six of eight men genes, encoding phylloquinone/mq biosynthetic enzymes, are missing from the g. ... | 2005 | 15955532 |
| photosystem i from the unusual cyanobacterium gloeobacter violaceus. | photosystem i (ps i) from the primitive cyanobacterium gloeobacter violaceus has been purified and characterised. despite the fact that the isolated complexes have the same subunit composition as complexes from other cyanobacteria, the amplitude of flash-induced absorption difference spectra indicates a much bigger antenna size with about 150 chlorophylls per p700 as opposed to the usual 90. image analysis of the ps i preparation from gloeobacter reveals that the ps i particles exist both in a t ... | 2002 | 16228529 |
| carotenoid biosynthesis in gloeobacter violaceus pcc4721 involves a single crti-type phytoene desaturase instead of typical cyanobacterial enzymes. | gloeobacter violaceus is a cyanobacterium isolated from other groups by lack of thylakoids and unique structural features of its photosynthetic protein complexes. carotenoid biosynthesis has been investigated with respect to the carotenoids formed and the genes and enzymes involved. carotenoid analysis identified ss-carotene as major carotenoid and echinenone as a minor component. this composition is quite unique and the cellular amounts are up to 10-fold lower than in other unicellular cyanobac ... | 2005 | 16235086 |
| chromophore attachment to phycobiliprotein beta-subunits: phycocyanobilin:cysteine-beta84 phycobiliprotein lyase activity of cpes-like protein from anabaena sp. pcc7120. | the gene alr0617, from the cyanobacterium anabaena sp. pcc7120, which is homologous to cpes from gloeobacter violaceus pcc 7421, fremyella diplosiphon (calothrix pcc7601), and synechococcus sp. wh8102, and to cpcs from synechococcus sp. pcc7002, was overexpressed in escherichia coli. cpes acts as a phycocyanobilin: cys-beta84-phycobiliprotein lyase that can attach, in vitro and in vivo, phycocyanobilin (pcb) to cysteine-beta84 of the apo-beta-subunits of c-phycocyanin (cpcb) and phycoerythrocyan ... | 2006 | 16452471 |
| the phycocyanin-associated rod linker proteins of the phycobilisome of gloeobacter violaceus pcc 7421 contain unusually located rod-capping domains. | gloeobacter violaceus pcc 7421 is a unique cyanobacterium that has no thylakoids and whose genome has been sequenced [y. nakamura, t. kaneko, s. sato, m. mimuro, h. miyashita, t. tsuchiya, s. sasamoto, a. watanabe, k. kawashima, y. kishida, c. kiyokawa, m. kohara, m. matsumoto, a. matsuno, n. nakazaki, s. shimpo, c. takeuchi, m. yamada, s. tabata, complete genome structure of gloeobacter violaceus pcc 7421, a cyanobacterium that lacks thylakoids. dna research 10 (2003) 137-145]. phycobilisomes o ... | 2006 | 16617515 |
| new linker proteins in phycobilisomes isolated from the cyanobacterium gloeobacter violaceus pcc 7421. | two new linker proteins were identified by peptide mass fingerprinting in phycobilisomes isolated from the cyanobacterium gloeobacter violaceus pcc 7421. the proteins were products of glr1262 and glr2806. three tandem phycocyanin linker motifs similar to cpcc were present in each. the glr1262 product most probably functions as a rod linker connecting phycoerythrin and phycocyanin, while the glr2806 product may function as a rod-core linker. we have designated these two proteins cpeg and cpcj, re ... | 2006 | 16714023 |
| carotenoid biosynthesis in cyanobacteria: structural and evolutionary scenarios based on comparative genomics. | carotenoids are widely distributed pigments in nature and their biosynthetic pathway has been extensively studied in various organisms. the recent access to the overwhelming amount genomic data of cyanobacteria has given birth to a novel approach called comparative genomics. the putative enzymes involved in the carotenoid biosynthesis among the cyanobacteria were determined by similarity-based tools. the reconstruction of biosynthetic pathway was based on the related enzymes. it is interesting t ... | 2006 | 16967101 |
| a prokaryotic proton-gated ion channel from the nicotinic acetylcholine receptor family. | ligand-gated ion channels (lgics) mediate excitatory and inhibitory transmission in the nervous system. among them, the pentameric or 'cys-loop' receptors (plgics) compose a family that until recently was found in only eukaryotes. yet a recent genome search identified putative homologues of these proteins in several bacterial species. here we report the cloning, expression and functional identification of one of these putative homologues from the cyanobacterium gloeobacter violaceus. it was expr ... | 2007 | 17167423 |
| the presence of multidomain linkers determines the bundle-shape structure of the phycobilisome of the cyanobacterium gloeobacter violaceus pcc 7421. | the complete genome sequence of gloeobacter violaceus [nakamura et al. (2003a, b) dna res 10:37-45, 181-201] allows us to understand better the structure of the phycobilisomes (pbs) of this cyanobacterium. genomic analysis revealed peculiarities in these pbs: the presence of genes for two multidomain linker proteins, a core membrane linker with four repetitive sequences (rep domains), the absence of rod core linkers, two sets of phycocyanin (pc) alpha and beta subunits, two copies of a rod pc as ... | 2007 | 17310305 |
| identification and functional analysis of a phytoene desaturase gene from the extremely radioresistant bacterium deinococcus radiodurans. | the phytoene-related desaturases are the key enzymes in the carotenoid biosynthetic pathway. the gene encoding phytoene desaturase in the deinoxanthin synthesis pathway of deinococcus radiodurans was identified and characterized. two putative phytoene desaturase homologues (dr0861 and dr0810) were identified by analysis of conserved amino acid regions, and the former displayed the highest identity (68 %) with phytoene desaturase of the cyanobacterium gloeobacter violaceus. dr0861 gene knockout a ... | 2007 | 17464079 |
| the psba gene family responds differentially to light and uvb stress in gloeobacter violaceus pcc 7421, a deeply divergent cyanobacterium. | gloeobacter violaceus pcc 7421 is a slow-growing cyanobacterium which lacks thylakoid membranes, but whose five-membered psba gene family encodes three isoform variants of the psba (d1) reaction center protein of photosystem ii. under standard culture conditions gloeobacter exhibits photosystem ii electron transport, but several clear modifications in the redox potential of key cofactors bound by the psba protein are manifested in the flash-fluorescence characteristics. in other cyanobacteria dy ... | 2008 | 17964531 |
| energy transfer processes in gloeobacter violaceus pcc 7421 that possesses phycobilisomes with a unique morphology. | we examined energy transfer dynamics in phycobilisomes (pbss) of cyanobacteria in relation to the morphology and pigment compositions of pbss. we used gloeobacter violaceus pcc 7421 and measured time-resolved fluorescence spectra in three types of samples, i.e., intact cells, pbss, and rod assemblies separated from cores. fremyella diplosiphon, a cyanobacterial species well known for its complementary chromatic adaptation, was used for comparison after growing under red or green light. spectral ... | 2008 | 18039461 |
| cgfs-type monothiol glutaredoxins from the cyanobacterium synechocystis pcc6803 and other evolutionary distant model organisms possess a glutathione-ligated [2fe-2s] cluster. | when produced in escherichia coli, the cgfs-type monothiol grxs from this organism (ecgrx4p) and the model cyanobacterium synechocystis (sygrx3p) exist as a dimeric iron-sulfur containing holoprotein or as a monomeric apoprotein in solution. spectroscopic and site-directed mutagenesis analyses show that the sygrx3 holoprotein contains a subunit-bridging [2fe-2s] cluster that is ligated by the catalytic cysteine located in the cgfs motif of each monomer and the cysteines of two molecules of gluta ... | 2007 | 18044966 |
| modular design of cys-loop ligand-gated ion channels: functional 5-ht3 and gaba rho1 receptors lacking the large cytoplasmic m3m4 loop. | cys-loop receptor neurotransmitter-gated ion channels are pentameric assemblies of subunits that contain three domains: extracellular, transmembrane, and intracellular. the extracellular domain forms the agonist binding site. the transmembrane domain forms the ion channel. the cytoplasmic domain is involved in trafficking, localization, and modulation by cytoplasmic second messenger systems but its role in channel assembly and function is poorly understood and little is known about its structure ... | 2008 | 18227272 |
| oxygen evolution in the thylakoid-lacking cyanobacterium gloeobacter violaceus pcc 7421. | the oxygen-evolving reactions of the thylakoid-lacking cyanobacterium gloeobacter violaceus pcc 7421 were compared with those of synechocystis sp. pcc 6803. four aspects were considered: sequence conservation in three extrinsic proteins for oxygen evolution, steady-state oxygen-evolving activity, charge recombination reactions, i.e., thermoluminescence and oscillation patterns of delayed luminescence on a second time scale and delayed fluorescence on the nanosecond time scale at -196 degrees c. ... | 2008 | 18298941 |
| two unique cyanobacteria lead to a traceable approach of the first appearance of oxygenic photosynthesis. | the evolutionary route from anoxygenic photosynthetic bacteria to oxygenic cyanobacteria is discontinuous in terms of photochemical/photophysical reaction systems. it is difficult to describe this transition process simply because there are no recognized intermediary organisms between the two bacterial groups. gloeobacter violaceus pcc 7421 might be a model organism that is suitable for analysis because it still possesses primordial characteristics such as the absence of thylakoid membranes. who ... | 2008 | 18568415 |
| plastocyanin-ferredoxin oxidoreduction and endosymbiotic gene transfer. | sequence similarities of proteins associated with plastocyanin-ferredoxin oxidoreduction (pcfdor) activity of photosystem i (psi) were grouped and compared. psaa, psab, psac, and petg represent genes that have been retained in the chloroplasts of both green- and red-lineage species. psad, psae, psaf, and petf represent genes that have been retained in the chloroplast of red-lineage species, but have been transferred to the nuclear genome of green-lineage species. translated sequences from red- a ... | 2008 | 18661249 |
| characterization of cyanobacterial carotenoid ketolase crtw and hydroxylase crtr by complementation analysis in escherichia coli. | the pathway from beta-carotene to astaxanthin is a crucial step in the synthesis of astaxanthin, a red antioxidative ketocarotenoid that confers beneficial effects on human health. two enzymes, a beta-carotene ketolase (carotenoid 4,4'-oxygenase) and a beta-carotene hydroxylase (carotenoid 3,3'-hydroxylase), are involved in this pathway. cyanobacteria are known to utilize the carotenoid ketolase crtw and/or crto, and the carotenoid hydroxylase crtr. here, we compared the catalytic functions of c ... | 2008 | 18987067 |
| x-ray structure of a pentameric ligand-gated ion channel in an apparently open conformation. | pentameric ligand-gated ion channels from the cys-loop family mediate fast chemo-electrical transduction, but the mechanisms of ion permeation and gating of these membrane proteins remain elusive. here we present the x-ray structure at 2.9 a resolution of the bacterial gloeobacter violaceus pentameric ligand-gated ion channel homologue (glic) at ph 4.6 in an apparently open conformation. this cationic channel is known to be permanently activated by protons. the structure is arranged as a funnel- ... | 2009 | 18987633 |
| comparative analysis of fatty acid desaturases in cyanobacterial genomes. | fatty acid desaturases are enzymes that introduce double bonds into the hydrocarbon chains of fatty acids. the fatty acid desaturases from 37 cyanobacterial genomes were identified and classified based upon their conserved histidine-rich motifs and phylogenetic analysis, which help to determine the amounts and distributions of desaturases in cyanobacterial species. the filamentous or n(2)-fixing cyanobacteria usually possess more types of fatty acid desaturases than that of unicellular species. ... | 2008 | 19096516 |
| transcription of a "silent" cyanobacterial psba gene is induced by microaerobic conditions. | cyanobacteria, contrary to higher plants, have a small psba gene family encoding the reaction centre d1 protein subunit of photosystem ii, the first macromolecular pigment-protein complex of the photosynthetic electron transport chain. modulation of expression of multiple psba genes in the family allows cyanobacteria to adapt to changing environmental conditions. to date, two different strategies for regulation of the psba genes have emerged. one, characterized in synechocystis pcc6803 and gloeo ... | 2009 | 19124001 |
| diversity of beta-propeller phytase genes in the intestinal contents of grass carp provides insight into the release of major phosphorus from phytate in nature. | phytate is the most abundant organic phosphorus compound in nature, and microbial mineralization of phytate by phytase is a key process for phosphorus recycling in the biosphere. in the present study, beta-propeller phytase (bpp) gene fragments were readily amplified from the intestinal contents of grass carp (ctenopharyngodon idellus) directly or from phytate-degrading isolates from the same source, confirming the widespread occurrence of bpp in aquatic communities. the amounts of sequences col ... | 2009 | 19151187 |
| the photocycle and proton translocation pathway in a cyanobacterial ion-pumping rhodopsin. | the genome of thylakoidless cyanobacterium gloeobacter violaceus encodes a fast-cycling rhodopsin capable of light-driven proton transport. we characterize the dark state, the photocycle, and the proton translocation pathway of gr spectroscopically. the dark state of gr contains predominantly all-trans-retinal and, similar to proteorhodopsin, does not show the light/dark adaptation. we found an unusually strong coupling between the conformation of the retinal and the site of glu132, the homolog ... | 2009 | 19217863 |
| prolamellar bodies formed by cyanobacterial protochlorophyllide oxidoreductase in arabidopsis. | in angiosperms, chlorophyll biosynthesis is light dependent. a key factor in this process is protochlorophyllide oxidoreductase (por), which requires light to catalyze the reduction of protochlorophyllide to chlorophyllide. it is believed that this protein originated from an ancient cyanobacterial enzyme that was introduced into proto-plant cells during the primary symbiosis. here we report that pors from the cyanobacteria gloeobacter violaceus pcc7421 and synechocystis sp. pcc6803 function in p ... | 2009 | 19222806 |
| protein signatures (molecular synapomorphies) that are distinctive characteristics of the major cyanobacterial clades. | a combination of phylogenomic and signature sequence-based (or phenetic) approaches was used to understand the evolutionary relationships among cyanobacteria. phylogenetic trees were constructed for 34 cyanobacteria whose genomes have been sequenced, based on concatenated sequences for 45 conserved proteins and also the 16s rrna gene. in parallel, sequence alignments of various proteins were examined to identify conserved indels (i.e. molecular signatures or synapomorphies) that are specific for ... | 2009 | 19622649 |
| loop 2 structure in glycine and gaba(a) receptors plays a key role in determining ethanol sensitivity. | the present study tests the hypothesis that the structure of extracellular domain loop 2 can markedly affect ethanol sensitivity in glycine receptors (glyrs) and gamma-aminobutyric acid type a receptors (gaba(a)rs). to test this, we mutated loop 2 in the alpha1 subunit of glyrs and in the gamma subunit of alpha1beta2gamma2gaba(a)rs and measured the sensitivity of wild type and mutant receptors expressed in xenopus oocytes to agonist, ethanol, and other agents using two-electrode voltage clamp. r ... | 2009 | 19656948 |
| variations in photosystem i properties in the primordial cyanobacterium gloeobacter violaceus pcc 7421. | we compared the optical properties of the trimeric photosystem (ps) i complexes of the primordial cyanobacterium gloeobacter violaceus pcc 7421 with those of synechocystis sp. pcc 6803. gloeobacter violaceus ps i showed (1) a shorter difference maximum of p700 by approximately 2 nm, (2) a smaller antenna size by approximately 10 chlorophyll (chl) a molecules and (3) an absence of red chls. the energy transfer kinetics in the antennae at physiological temperatures were very similar between the tw ... | 2010 | 19769578 |
| reconstitution of gloeobacter violaceus rhodopsin with a light-harvesting carotenoid antenna. | we show that salinixanthin, the light-harvesting carotenoid antenna of xanthorhodopsin, can be reconstituted into the retinal protein from gloeobacter violaceus expressed in escherichia coli. reconstitution of gloeobacter rhodopsin with the carotenoid is accompanied by characteristic absorption changes and the appearance of cd bands similar to those observed for xanthorhodopsin that indicate immobilization and twist of the carotenoid in the binding site. as in xanthorhodopsin, the carotenoid fun ... | 2009 | 19842712 |
| crystal structure of the extracellular domain of a bacterial ligand-gated ion channel. | the crystal structure of the extracellular domain (ecd) of the pentameric ligand-gated ion-channel from gloeobacter violaceus (glic) was solved at neutral ph at 2.3 a resolution in two crystal forms, showing a surprising hexameric quaternary structure with a 6-fold axis replacing the expected 5-fold axis. while each subunit retains the usual beta-sandwich immunoglobulin-like fold, small deviations from the whole glic structure indicate zones of differential flexibility. the changes in interface ... | 2010 | 19917292 |
| anesthetic sensitivity of the gloeobacter violaceus proton-gated ion channel. | a prokaryotic member of the gamma-aminobutyric acid type a receptor superfamily (glic) was recently cloned from the cyanobacterium gloeobacter violaceus, its function characterized, and its 3-dimensional x-ray diffraction crystal structure determined. we report its modulation by 9 anesthetics using 2-electrode voltage clamping in xenopus laevis oocytes. desflurane, halothane, isoflurane, sevoflurane, and propofol inhibited currents through glic at and below concentrations used clinically. hill n ... | 2010 | 19933531 |
| over-expression, purification and characterization of an asc-1 homologue from gloeobacter violaceus. | the human alanine-serine-cysteine transporter 1 (asc-1) belongs to the slc7a family of solute carrier transporters. asc-1 mediates the uptake of d-serine in an exchanger-type fashion, coupling the process to the release of alanine and cysteine. among the bacterial asc-1 homologues, one transporter shows a significantly higher sequence identity (35%) than other bacterial homologues. therefore, this homologue from gloeobacter violaceus might represent the best bacterial target for structural studi ... | 2010 | 20074644 |
| low-temperature ftir study of gloeobacter rhodopsin: presence of strongly hydrogen-bonded water and long-range structural protein perturbation upon retinal photoisomerization. | gloeobacter rhodopsin (gr) is a light-driven proton-pump protein similar to bacteriorhodopsin (br), found in gloeobacter violaceus pcc 7421, a primitive cyanobacterium. in this paper, structural changes of gr following retinal photoisomerization are studied by means of low-temperature fourier-transform infrared (ftir) spectroscopy. the initial motivation was to test our hypothesis that proton-pumping rhodopsins possess strongly hydrogen-bonded water molecules in the active center. water o-d stre ... | 2010 | 20230053 |
| characterization of two cytochrome b6 proteins from the cyanobacterium gloeobacter violaceus pcc 7421. | in the genome of the untypical cyanobacterium gloeobacter violaceus pcc 7421 two potential cytochrome b (6) proteins petb1 and petb2 are encoded. such a situation has not been observed in cyanobacteria, algae and higher plants before, and both proteins are not characterized at all yet. here, we show that both apo-proteins bind heme with high affinity and the spectroscopic characteristics of both holo-proteins are distinctive for cytochrome b (6) proteins. however, while in petb2 one histidine re ... | 2010 | 20237831 |
| one-microsecond molecular dynamics simulation of channel gating in a nicotinic receptor homologue. | recently discovered bacterial homologues of eukaryotic pentameric ligand-gated ion channels, such as the gloeobacter violaceus receptor (glic), are increasingly used as structural and functional models of signal transduction in the nervous system. here we present a one-microsecond-long molecular dynamics simulation of the glic channel ph stimulated gating mechanism. the crystal structure of glic obtained at acidic ph in an open-channel form is equilibrated in a membrane environment and then inst ... | 2010 | 20308576 |
| anesthetic binding in a pentameric ligand-gated ion channel: glic. | cys-loop receptors are molecular targets of general anesthetics, but the knowledge of anesthetic binding to these proteins remains limited. here we investigate anesthetic binding to the bacterial gloeobacter violaceus pentameric ligand-gated ion channel (glic), a structural homolog of cys-loop receptors, using an experimental and computational hybrid approach. tryptophan fluorescence quenching experiments showed halothane and thiopental binding at three tryptophan-associated sites in the extrace ... | 2010 | 20858424 |
| computational analysis of lexa regulons in cyanobacteria. | the transcription factor lexa plays an important role in the sos response in escherichia coli and many other bacterial species studied. although the lexa gene is encoded in almost every bacterial group with a wide range of evolutionary distances, its precise functions in each group/species are largely unknown. more recently, it has been shown that lexa genes in two cyanobacterial genomes nostoc sp. pcc 7120 and synechocystis sp. pcc 6803 might have distinct functions other than the regulation of ... | 2010 | 20920248 |
| reconstitution of gloeobacter rhodopsin with echinenone: role of the 4-keto group. | in previous work, we reconstituted salinixanthin, the c(40)-carotenoid acyl glycoside that serves as a light-harvesting antenna to the light-driven proton pump xanthorhodopsin, into a different protein, gloeobacter rhodopsin expressed in escherichia coli, and demonstrated that it transfers energy to the retinal chromophore [imasheva, e. s., et al. (2009) biochemistry 48, 10948]. the key to binding of salinixanthin was the accommodation of its ring near the retinal β-ionone ring. here we examine ... | 2010 | 20942439 |
| molecular dynamics and brownian dynamics investigation of ion permeation and anesthetic halothane effects on a proton-gated ion channel. | bacterial gloeobacter violaceus pentameric ligand-gated ion channel (glic) is activated to cation permeation upon lowering the solution ph. its function can be modulated by anesthetic halothane. in the present work, we integrate molecular dynamics (md) and brownian dynamics (bd) simulations to elucidate the ion conduction, charge selectivity, and halothane modulation mechanisms in glic, based on recently resolved x-ray crystal structures of the open-channel glic. md calculations of the potential ... | 2010 | 20979415 |
| pore opening and closing of a pentameric ligand-gated ion channel. | nerve signaling in humans and chemical sensing in bacteria both rely on the controlled opening and closing of the ion-conducting pore in pentameric ligand-gated ion channels. with the help of a multiscale simulation approach that combines mixed elastic network model calculations with molecular dynamics simulations, we study the opening and closing of the pore in gloeobacter violaceus channel glic at atomic resolution. in our simulations of the glic transmembrane domain, we first verify that the ... | 2010 | 21041674 |
| interactions of linker proteins with the phycobiliproteins in the phycobilisome substructures of gloeobacter violaceus. | gloeobacter violaceus pcc 7421 is a unicellular oxygenic photosynthetic organism, which precedes the diversification of cyanobacteria in the phylogenetic tree. it is the only cyanobacterium that does not contain internal membranes. the unique structure of the rods of the phycobilisome (pbs), grouped as one bundle of six parallel rods, distinguishes g. violaceus from the other pbs-containing cyanobacteria. it has been proposed that unique multidomain rod-linkers are responsible for this peculiarl ... | 2010 | 21136295 |
| ion selectivity mechanism in a bacterial pentameric ligand-gated ion channel. | the proton-gated ion channel from gloeobacter violaceus (glic) is a prokaryotic homolog of the eukaryotic nicotinic acetylcholine receptor that responds to the binding of neurotransmitter acetylcholine and mediates fast signal transmission. recent emergence of a high-resolution crystal structure of glic captured in a potentially open state allowed detailed, atomic-level insight into ion conduction and selectivity mechanisms in these channels. herein, we have examined the barriers to ion conducti ... | 2011 | 21244835 |
| x-ray structures of general anaesthetics bound to a pentameric ligand-gated ion channel. | general anaesthetics have enjoyed long and widespread use but their molecular mechanism of action remains poorly understood. there is good evidence that their principal targets are pentameric ligand-gated ion channels (plgics) such as inhibitory gaba(a) (γ-aminobutyric acid) receptors and excitatory nicotinic acetylcholine receptors, which are respectively potentiated and inhibited by general anaesthetics. the bacterial homologue from gloeobacter violaceus (glic), whose x-ray structure was recen ... | 2011 | 21248852 |
| a twin-track approach has optimized proton and hydride transfer by dynamically coupled tunneling during the evolution of protochlorophyllide oxidoreductase. | protein dynamics are crucial for realizing the catalytic power of enzymes, but how enzymes have evolved to achieve catalysis is unknown. the light-activated enzyme protochlorophyllide oxidoreductase (por) catalyzes sequential hydride and proton transfers in the photoexcited and ground states, respectively, and is an excellent system for relating the effects of motions to catalysis. here, we have used the temperature dependence of isotope effects and solvent viscosity measurements to analyze the ... | 2011 | 21317291 |
| linking of glycine receptor transmembrane segments three and four allows assignment of intrasubunit-facing residues. | glycine receptors (glyrs) are pentameric ligand-gated ion channels that mediate inhibitory neurotransmission in the brain and spinal cord and are targets of alcohols and anesthetics. the transmembrane (tm) domain of glyr subunits is composed of four α-helical segments (tm1-4), but there are conflicting data about the orientation of tm3 and tm4 and, therefore, also the proximity of residues (e.g., a288) that are important for alcohol and anesthetic effects. in the present study, we investigated t ... | 2010 | 21326622 |
| structure of the m2 transmembrane segment of glic, a prokaryotic cys loop receptor homologue from gloeobacter violaceus, probed by substituted cysteine accessibility. | glic is a homopentameric proton-gated, prokaryotic homologue of the cys loop receptor family of neurotransmitter-gated ion channels. recently, crystal structures of glic hypothesized to represent an open channel state were published. to explore the channel structure in functional glic channels, we tested the ability of p-chloromercuribenzenesulfonate to react with 30 individual cysteine substitution mutants in and flanking the m2 channel-lining segment in the closed state (ph 7.5) and in a subma ... | 2011 | 21362624 |
| microsecond simulations indicate that ethanol binds between subunits and could stabilize an open-state model of a glycine receptor. | cys-loop receptors constitute a superfamily of ion channels gated by ligands such as acetylcholine, serotonin, glycine, and ?-aminobutyric acid. all of these receptors are thought to share structural characteristics, but due to high sequence variation and limited structure availability, our knowledge about allosteric binding sites is still limited. these sites are frequent targets of anesthetic and alcohol molecules, and are of high pharmacological importance. we used molecular simulations to st ... | 2011 | 21463577 |
| the plasma membrane of the cyanobacterium gloeobacter violaceus contains segregated bioenergetic domains. | the light reactions of oxygenic photosynthesis almost invariably take place in the thylakoid membranes, a highly specialized internal membrane system located in the stroma of chloroplasts and the cytoplasm of cyanobacteria. the only known exception is the primordial cyanobacterium gloeobacter violaceus, which evolved before the appearance of thylakoids and harbors the photosynthetic complexes in the plasma membrane. thus, studies on g. violaceus not only shed light on the evolutionary origin and ... | 2011 | 21642550 |
| atp regeneration system using e. coli atp synthase and gloeobacter rhodopsin and its stability. | great efforts in using non-photosynthetic bacteria as light-utilizing bacteria for producing biomaterials have been developed recently as increasing interest in renewable resources such as light energy. with respect to producing bio-materials industrially such as food ingredients and amino acids, huge amount of adenosine-5'-triphosphate (atp) is required. in this work, we developed a bio-atp-synthesis system using atp synthase of escherichia coil as a biocatalyst and a microbial rhodopsin which ... | 2011 | 21780438 |
| engineering a prokaryotic cys-loop receptor with a third functional domain. | prokaryotic members of the cys-loop receptor ligand-gated ion channel superfamily were recently identified. previously, cys-loop receptors were only known from multicellular organisms (metazoans). contrary to the metazoan cys-loop receptors, the prokaryotic ones consist of an extracellular (ecd) and a transmembrane domain (tmd), lacking the large intracellular domain (icd) present in metazoa (between transmembrane segments m3 and m4). using a chimera approach, we added the 115 amino acid icd fro ... | 2011 | 21844195 |
| nmr structure and dynamics of a designed water-soluble transmembrane domain of nicotinic acetylcholine receptor. | the nicotinic acetylcholine receptor (nachr) is an important therapeutic target for a wide range of pathophysiological conditions, for which rational drug designs often require receptor structures at atomic resolution. recent proof-of-concept studies demonstrated a water-solubilization approach to structure determination of membrane proteins by nmr (slovic et al., pnas, 101: 1828-1833, 2004; ma et al., pnas, 105: 16537-42, 2008). we report here the computational design and experimental character ... | 2011 | 22155685 |
| unravelling the conformational plasticity of the extracellular domain of a prokaryotic nachr homologue in solution by nmr. | pentameric ligand-gated ion channels (plgics) of the cys loop family are transmembrane glycoproteins implicated in a variety of biological functions. here, we present a solution nmr study of the extracellular domain of a prokaryotic plgic homologue from the bacterium gloeobacter violaceus that is found to be a monomer in solution. | 2011 | 22007668 |
| molecular dissection of cl--selective cys-loop receptor points to components that are dispensable or essential for channel activity. | cys-loop receptors are pentameric ligand-gated ion channels (plgics) that bind neurotransmitters to open an intrinsic transmembrane ion channel pore. the recent crystal structure of a prokaryotic plgic from the cyanobacterium gloeobacter violaceus (glic) revealed that it naturally lacks an n-terminal extracellular α helix and an intracellular domain that are typical of eukaryotic plgics. glic does not respond to neurotransmitters acting at eukaryotic plgics but is activated by protons. to determ ... | 2011 | 21987577 |
| Isoflurane alters the structure and dynamics of GLIC. | Pentameric ligand-gated ion channels are targets of general anesthetics. Although the search for discrete anesthetic binding sites has achieved some degree of success, little is known regarding how anesthetics work after the events of binding. Using the crystal structures of the bacterial Gloeobacter violaceus pentameric ligand-gated ion channel (GLIC), which is sensitive to a variety of general anesthetics, we performed multiple molecular dynamics simulations in the presence and absence of the ... | 2011 | 22004744 |
| identification of an oxygenic reaction center psbadc operon in the cyanobacterium gloeobacter violaceus pcc 7421. | gloeobacter violaceus, the earliest diverging oxyphotobacterium (cyanobacterium) on the 16s ribosomal rna tree, has five copies of the photosystem ii psba gene encoding the d1 reaction center protein subunit. these copies are widely distributed throughout the 4.6 mbp genome with only one copy colocalizing with other psii subunits, in marked contrast to all other psba genes in all publicly available sequenced genomes. a clustering of two other psb genes around psba3 (glr2322) is unique to gloeoba ... | 2011 | 21903678 |
| Cys-Loop Receptor Channel Blockers Also Block GLIC. | The Gloeobacter ligand-gated ion channel (GLIC) is a bacterial homolog of vertebrate Cys-loop ligand-gated ion channels. Its pore-lining region in particular has a high sequence homology to these related proteins. Here we use electrophysiology to examine a range of compounds that block the channels of Cys-loop receptors to probe their pharmacological similarity with GLIC. The data reveal that a number of these compounds also block GLIC, although the pharmacological profile is distinct from these ... | 2011 | 22208189 |