Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| role of the colorless polypeptides in phycobilisome reconstitution from separated phycobiliproteins. | a phycoerythrin (pe) and phycocyanin (pc) mixture was separated from allophycocyanin on calcium phosphate chromatography from completely dissociated phycobilisomes of the blue-green alga, nostoc sp. after dialysis of the pe-pc mixture in 0.75 m potassium phosphate, ph 7, which allows reassociation of the dissociated pigment-proteins, complexes of pe and pc in a 2:1 m ratio (pe/pc complex) as well as complexes predominantly of pc (pc/pe complex) were then separated by sedimentation on linear sucr ... | 1982 | 16662378 |
| allophycocyanin i and the 95 kilodalton polypeptide : the bridge between phycobilisomes and membranes. | allophycocyanin was isolated from dissociated phycobilisomes from nostoc sp. and was separated into allophycocyanin i, ii, iii, and b as described elsewhere. if the separation of the proteins following phycobilisome isolation is done in the presence of the protease inhibitor, phenylmethylsulfonylfluoride, associated with allophycocyanin i are two colored polypeptides of 95 kilodalton (kd) and 80 kd, belonging to the class of group i polypeptides as defined by tandeau de marsac and cohen-bazire ( ... | 1982 | 16662612 |
| isolation and characterization of the central component of the phycobilisome core of nostoc sp. | freshly isolated allophycocyanin is recovered from linear sucrose gradients made in 0.75 molar potassium phosphate buffer (ph 7.0) in three sizes: 19s, 10.3s, and 5.5s. the largest aggregate is a complex of a 680 nm fluorescing allophycocyanin i in the form (alphabeta)(3)gamma, where gamma is the 95 kilodalton (kd) polypeptide, and two 660 nanometer fluorescing allophycocyanin ii (alphabeta)(3) molecules; the complex, stabilized in high phosphate concentrations, fluoresces maximally at 675 nanom ... | 1982 | 16662613 |
| growth and chromatic adaptation of nostoc sp. strain mac and the pigment mutant r-mac. | a spontaneous, stable, pigmentation mutant of nostoc sp. strain mac was isolated. under various growth conditions, this mutant, r-mac, had similar phycoerythrin contents (relative to allophycocyanin) but significantly lower phycocyanin contents (relative to allophycocyanin) than the parent strain. in saturating white light, the mutant grew more slowly than the parent strain. in nonsaturating red light, mac grew with a shorter generation time than the mutant; however, r-mac grew more quickly in n ... | 1982 | 16662715 |
| role of the colorless polypeptides in phycobilisome assembly in nostoc sp. | we have identified the function of the ;extra' polypeptides involved in phycobilisome assembly in nostoc sp. these phycobilisomes, as those of other cyanobacteria, are composed of an allophycocyanin core, phycoerythrin- and phycocyanin-containing rods, and five additional polypeptides of 95, 34.5, 34, 32, and 29 kilodaltons. the 95 kilodalton polypeptide anchors the phycobilisome to the thylakoid membrane (rusckowski, zilinskas 1982 plant physiol 70: 1055-1059); the 29 kilodalton polypeptide att ... | 1983 | 16662834 |
| constant phycobilisome size in chromatically adapted cells of the cyanobacterium tolypothrix tenuis, and variation in nostoc sp. | phycobilisomes of tolypothrix tenuis, a cyanobacterium capable of complete chromatic adaptation, were studied from cells grown in red and green light, and in darkness. the phycobilisome size remained constant irrespective of the light quality. the hemidiscoidal phycobilisomes had an average diameter of about 52 nanometers and height of about 33 nanometers, by negative staining. the thickness was equivalent to a phycocyanin molecule (about 10 nanometers). the molar ratio of allophycocyanin, relat ... | 1985 | 16664550 |
| the immunologically conserved phycobilisome-thylakoid linker polypeptide. | we have isolated phycobilisomes from two classes of red algae, several subdivisions of the cyanobacteria, and the cyanelles of cyanophora paradoxa. in addition to the major light harvesting biliproteins, these phycobilisomes also contain several other polypeptides, the largest of which ranges from 75 to 120 kilodaltons in the different species surveyed. this protein, previously isolated and characterized from three species, was shown to be the final emitter of excitation energy in phycobilisomes ... | 1986 | 16664726 |
| immunological conservation of phycobilisome rod linker polypeptides. | monospecific polyclonal antibodies raised against the phycobilisome rod linker polypeptides of nostoc sp. were used to assess structural similarities among phycobilisome linker proteins from diverse, phycobilisome-containing organisms. while a remarkable conservation of antigenic determinants was demonstrated for two of these rod linker proteins, the third linker polypeptide appeared to be conserved only among closely related species. | 1987 | 16665695 |
| sodium requirement for photosynthesis and its relationship with dinitrogen fixation and the external co(2) concentration in cyanobacteria. | cells of anabaena pcc 7119 and of a mutant strain of nostoc muscorum unable to fix dinitrogen, grown at ph 8 and under low co(2) tension (air), showed a reduced capacity for photosynthesis when cultured in the absence of sodium, this inhibition being followed by symptoms of photooxidation, such as chlorosis, oxygen consumption in the light, and decrease of superoxide dismutase activity. the impairment of photosynthesis preceded that of nitrogenase activity, indicating that the requirement for so ... | 1987 | 16665740 |
| n-terminus conservation in the terminal pigment of phycobilisomes from a prokaryotic and eukaryotic alga. | high molecular weight polypeptides from phycobilisomes, believed to be involved in facilitating the energy flow from phycobilisomes to thylakoids, are conserved in the prokaryote nostoc sp. and the eukaryote porphyridium cruentum. partial n-terminal sequence analysis of the phycobilisome-polypeptides of nostoc (94 kilodalton) and porphyridium (92 kilodalton) revealed 55% identity in the first 20 residues, but no significant homology with sequences of other phycobiliproteins or phycobilisome-link ... | 1988 | 16666079 |
| a new uv-a/b protecting pigment in the terrestrial cyanobacterium nostoc commune. | a new ultraviolet (uv)-a/b absorbing pigment with maxima at 312 and 330 nanometers from the cosmopolitan terrestrial cyanobacterium nostoc commune is described. the pigment is found in high amounts (up to 10% of dry weight) in colonies grown under solar uv radiation but only in low concentrations in laboratory cultures illuminated by artificial light without uv. its experimental induction by uv as well as its capacity to efficiently protect nostoc against uv radiation is reported. | 1988 | 16666420 |
| occurrence and localization of phycoerythrin in symbiotic nostoc of cycas revoluta and in the free-living isolated nostoc 7422. | the phycobiliprotein phycoerythrin was localized in symbiotic and free-living nostoc of the cycad cycas using immunocytochemistry. in symbiotic nostoc, phycoerythrin was associated with the thylakoid membranes of vegetative cells and absent from heterocysts. similar cellular/subcellular localization was observed between symbiotic nostoc and the free-living cycas isolate nostoc 7422. | 1989 | 16666621 |
| boron requirement in cyanobacteria : its possible role in the early evolution of photosynthetic organisms. | the effect of boron on heterocystous and nonheterocystous dinitrogen fixing cyanobacteria was examined. the absence of boron in culture media inhibited growth and nitrogenase activity in nodularia sp., chlorogloeopsis sp., and nostoc sp. cultures. examinations of boron-deficient cultures showed changes in heterocyst morphology. however, cultures of nonheterocystous cyanobacteria, gloeothece sp. and plectonema sp., grown in the absence of boron did not show any alteration in growth or nitrogenase ... | 1990 | 16667889 |
| n(2)-fixation by freshly isolated nostoc from coralloid roots of the cycad macrozamia riedlei (fisch. ex gaud.) gardn. | nitrogenase (ec 1.7.99.2) activity (acetylene reduction) and nitrogen fixation ((15)n(2) fixation) were measured in cyanobacteria freshly isolated from the coralloid roots of macrozamia riedlei (fisch. ex gaud.) gardn. light and gas phase oxygen concentration had marked interactive effects on activity, with higher (up to 100-fold) rates of acetylene reduction and (15)n(2) fixation in light. the relationship between ethylene formation and n(2)-fixation varied in the freshly isolated cyanobacteria ... | 1991 | 16668050 |
| a novel delta9 acyl-lipid desaturase, desc2, from cyanobacteria acts on fatty acids esterified to the sn-2 position of glycerolipids. | acyl-lipid desaturases are enzymes that convert a c-c single bond into a c=c double bond in fatty acids that are esterified to membrane-bound glycerolipids. four types of acyl-lipid desaturase, namely desa, desb, desc, and desd, acting at the delta12, delta15, delta9, and delta6 positions of fatty acids respectively, have been characterized in cyanobacteria. these enzymes are specific for fatty acids bound to the sn-1 position of glycerolipids. in the present study, we have cloned two putative g ... | 2006 | 16689682 |
| regulated expression of glutamyl-trna synthetase is directed by a mobile genetic element in the cyanobacterium tolypothrix sp. pcc 7601. | the genome of tolypothrix sp. pcc 7601 carries two copies of a novel insertion sequence, istosp1. one of the two copies is located upstream of the gene encoding glutamyl-trna synthetase, an enzyme playing a key role in protein and pigment synthesis. the tnpa gene of the is element and gltx were co-transcribed and their expression was transiently upregulated upon retrieval of the ammonium source irrespective of whether nitrate or no nitrogen source were available. the second copy is also transcri ... | 2006 | 16689802 |
| mutagenic definition of a papain-like catalytic triad, sufficiency of the n-terminal domain for single-site core catalytic enzyme acylation, and c-terminal domain for augmentative metal activation of a eukaryotic phytochelatin synthase. | phytochelatin (pc) synthases are gamma-glutamylcysteine (gamma-glu-cys) dipeptidyl transpeptidases that catalyze the synthesis of heavy metal-binding pcs, (gamma-glu-cys)ngly polymers, from glutathione (gsh) and/or shorter chain pcs. here it is shown through investigations of the enzyme from arabidopsis (arabidopsis thaliana; atpcs1) that, although the n-terminal half of the protein, alone, is sufficient for core catalysis through the formation of a single-site enzyme acyl intermediate, it is no ... | 2006 | 16714405 |
| screening and selection of most potent diazotrophic cyanobacterial isolate exhibiting natural tolerance to rice field herbicides for exploitation as biofertilizer. | periodic applications of heavy dosages of herbicides in modern rice-agriculture are a necessary evil for obtaining high crop productivity. such herbicides are not only detrimental to weeds but biofertilizer strains of diazotrophic cyanobacteria also. it is therefore, essential to screen and select such biofertilizer strains of diazotrophic cyanobacteria exhibiting natural tolerance to common rice-field herbicides that can be further improved by mutational techniques to make biofertilizer technol ... | 2006 | 16721882 |
| nitric oxide binding to prokaryotic homologs of the soluble guanylate cyclase beta1 h-nox domain. | the heme cofactor in soluble guanylate cyclase (sgc) is a selective receptor for no, an important signaling molecule in eukaryotes. the sgc heme domain has been localized to the n-terminal 194 amino acids of the beta1 subunit of sgc and is a member of a family of conserved hemoproteins, called the h-nox family (heme-nitric oxide and/or oxygen-binding domain). three new members of this family have now been cloned and characterized, two proteins from legionella pneumophila (l1 h-nox and l2 h-nox) ... | 2006 | 16728401 |
| heavy metal sorption by released polysaccharides and whole cultures of two exopolysaccharide-producing cyanobacteria. | the metal removal capacity of cultures of two capsulated, exopolysaccharide-producing cyanobacteria, cyanospira capsulata and nostoc pcc7936, were tested using copper (ii) as the model metal. c. capsulata cultures removed the greatest amount of copper, with a maximum per unit of biomass (q(max)) of 115.0+/-5.1 mg copper g(-1) of protein, compared with 85.0+/-3.2 removed with nostoc pcc7936 cultures. water solutions of pure polysaccharides (rpss) released into the culture medium by c. capsulata a ... | 2007 | 16758273 |
| retinal is formed from apo-carotenoids in nostoc sp. pcc7120: in vitro characterization of an apo-carotenoid oxygenase. | the sensory rhodopsin from anabaena (nostoc) sp. pcc7120 is the first cyanobacterial retinylidene protein identified. here, we report on nosaco (nostoc apo-carotenoid oxygenase), encoded by the orf (open reading frame) all4284, as the candidate responsible for the formation of the required chromophore, retinal. in contrast with the enzymes from animals, nosaco converts beta-apo-carotenals instead of beta-carotene into retinal in vitro. the identity of the enzymatic products was proven by hplc an ... | 2006 | 16759173 |
| the involvement of the antioxidant system in protection of desert cyanobacterium nostoc sp. against uv-b radiation and the effects of exogenous antioxidants. | in this study, we found that uv-b radiation decreased photosynthetic activity and boosted lipid peroxidation of desert nostoc sp., and exogenous chemicals (ascorbate acid (asc), n-acetylcysteine (nac), and sodium nitroprusside (snp)) had obvious protective effects on photosynthesis and membranes under uv-b radiation. high-concentration snp boosted the activities of antioxidant enzymes, but low-concentration snp reduced the activities of antioxidant enzymes. both nac and asc treatments of cells d ... | 2008 | 16759702 |
| process optimization for poly-beta-hydroxybutyrate production in a nitrogen fixing cyanobacterium, nostoc muscorum using response surface methodology. | a five-level-four-factor central composite rotary design was employed to find out the interactive effects of four variables, viz. concentrations of acetate, glucose and k2hpo4, and dark incubation period on poly-beta-hydroxybutyrate (phb) production in a n2-fixing cyanobacterium, nostoc muscorum. acetate, glucose and dark incubation period exhibited positive impacts on phb yield. using response surface methodology (rsm), a second order polynomial equation was obtained by multiple regression anal ... | 2007 | 16765593 |
| identification of nostoc punctiforme akinete-expressed genes using differential display. | akinetes are spore-like resting cells formed by certain filamentous cyanobacteria that have increased resistance to environmental stress. they can be found at low frequencies in dense cultures experiencing low light or phosphate limitation, but also form at high frequencies in a zwf mutant strain of nostoc punctiforme following dark incubation in the presence of fructose. the wild-type strain is capable of facultative heterotrophic growth under these conditions and does not form akinetes. to ide ... | 2006 | 16780565 |
| genetically modified cyanobacterium nostoc muscorum overproducing proline in response to salinity and osmotic stresses. | in the parent nostoc muscorum an active proline oxidase enzyme is required to assimilate exogenous proline as a fixed nitrogen source. cyanobacterial mutants, resistant to growth inhibitory action of proline analogue l-azetidine-2-carboxylate (ac-r), were deficient in proline oxidase activity, and were over-accumulators of proline. proline over-accumulation, resulting either from mutational acquisition of the ac-r phenotype, or from salinity-induced uptake of exogenous proline, confirmed enhance ... | 2006 | 16809859 |
| auxotrophic mutant of the cyanobacterium nostoc muscorum showing absolute requirement of cs+ or rb+ for diazotrophy and autotrophy. | caesium-resistant (cs(+)-r) mutant clones of the cyanobacterium nostoc muscorum were characterized for diazotrophic growth in a medium devoid of cs(+) or rb(+) or both. cs(+)-r phenotype suffered severe genetic damage of a pleiotropic nature affecting diazotrophic growth, chlorophyll a content, nitrogenase activity and photosynthetic o(2) evolution. mutation leading to development of cs(+)-r phenotype could be overcome by availability of cs(+)/rb(+). parent and mutant strains were similar with r ... | 2006 | 16847829 |
| screening of microalgae for species excreting norharmane, a manifold biologically active indole alkaloid. | a screening of microalgae strains is described, with the objective to discover more species besides the known cyanobacterium nodularia harveyana which excrete the manifold biologically active and co-mutagenic indole alkaloid norharmane (9h-pyrido(3,4-b)indole) into their environment. seven more cyanobacterial species, anabaena cylindrica, anabaena inaequalis, anabaenopsis siamensis, chroococcus minutus, nostoc carneum, nostoc commune and phormidium foveolarum, were newly discovered. the norharma ... | 2008 | 16872816 |
| mycobacterium tuberculosis transporter mmpl7 is a potential substrate for kinase pknd. | the mycobacterium tuberculosis serine/threonine protein kinases are attractive potential drug targets, and protein kinase d (pknd) is particularly interesting, as it is autophosphorylated on 11 residues, binds proteins containing forkhead associated domains, and contains a beta-propeller motif that likely functions as an anchoring sensor domain. we created a pknd knockout of a clinical m. tuberculosis isolate, and found that on in vitro phosphorylation of cell wall fractions it lacked a family o ... | 2006 | 16879801 |
| identification of carotenoid cleavage dioxygenases from nostoc sp. pcc 7120 with different cleavage activities. | carotenoid cleavage dioxygenases (ccds) are a class of enzymes that oxidatively cleave carotenoids into apocarotenoids. dioxygenases have been identified in plants and animals and produce a wide variety of cleavage products. despite what is known about apocarotenoids in higher organisms, very little is known about apocarotenoids and ccds in microorganisms. this study surveyed cleavage activities of ten putative carotenoid cleavage dioxygenases from five different cyanobacteria in recombinant esc ... | 2006 | 16920703 |
| three putative photosensory light, oxygen or voltage (lov) domains with distinct biochemical properties from the filamentous cyanobacterium anabaena sp. pcc 7120. | light, oxygen or voltage (lov) domains function as blue-light sensors in the phototropin family of photoreceptors found in plants, algae and bacteria. we detected putative lov domains (alr3170-lov, all2875-lov and alr1229-lov) in the genome of a filamentous cyanobacterium, anabaena sp. pcc 7120. these cyanobacterial lov domains are closely clustered with the known lov domains. alr3170-lov and a112875-lov carry the conserved cysteine residue unique to the photoactive lov, whereas alr1229-lov does ... | 2006 | 16922605 |
| identification of a diagnostic marker to detect freshwater cyanophages of filamentous cyanobacteria. | cyanophages are viruses that infect the cyanobacteria, globally important photosynthetic microorganisms. cyanophages are considered significant components of microbial communities, playing major roles in influencing host community diversity and primary productivity, terminating cyanobacterial water blooms, and influencing biogeochemical cycles. cyanophages are ubiquitous in both marine and freshwater systems; however, the majority of molecular research has been biased toward the study of marine ... | 2006 | 16957185 |
| metabolites produced by cyanobacteria belonging to several species of the family nostocaceae. | this paper provides a comprehensive overview of metabolites, including lipids and lipid-like compounds, nitrogen metabolites, oligopeptides and amino acid derivatives, produced by cyanobacteria of the genera anabaenopsis, aphanizomenon, aulosira, cylindrospermopsis, cylindrospermum, nodularia, and richelia of the family nostocaceae. | 2006 | 17004647 |
| allergenicity of airborne cyanobacteria phormidium fragile and nostoc muscorum. | in recent times, airborne microorganisms and their constituents have become prominent safety and health concern. ongoing climatic changes coupled with unwarranted human activities have significantly deteriorated the ambient air quality. in certain environments, airborne algae contribute significantly to the total biological load of the atmosphere, hitherto dominated by bacteria and fungi. present study was aimed to investigate the allergenic potency of two frequent viable algal forms i.e., phorm ... | 2008 | 17011621 |
| engineered cyanophycin synthetase (cpha) from nostoc ellipsosporum confers enhanced cpha activity and cyanophycin accumulation to escherichia coli. | the cyanophycin (cgp) synthetase gene (cphane1) of the transposon-induced argl mutant ne1 of the cyanobacterium nostoc ellipsosporum, which exhibits a cgp-leaky phenotype during diazotrophical growth, was cloned and expressed in escherichia coli strain top10. its amino acid sequence exhibited high similarities to cphas of other cyanobacteria. recombinant cells of e. coli, which harbored a fragment comprising the complete cphane1 gene plus 400 bp of its downstream region in colinear orientation t ... | 2006 | 17012590 |
| transient binding of plastocyanin to its physiological redox partners modifies the copper site geometry. | the transient complexes of plastocyanin with cytochrome f and photosystem i are herein used as excellent model systems to investigate how the metal sites adapt to the changes in the protein matrix in transient complexes that are involved in redox reactions. thus, both complexes from the cyanobacterium nostoc sp. pcc 7119 (former anabaena sp. pcc 7119) have been analysed by x-ray absorption spectroscopy. our data are consistent with a significant distortion of the trigonal pyramidal geometry of t ... | 2006 | 17064694 |
| microbial communities on glacier surfaces in svalbard: impact of physical and chemical properties on abundance and structure of cyanobacteria and algae. | microbial communities occurring in three types of supraglacial habitats--cryoconite holes, medial moraines, and supraglacial kames--at several glaciers in the arctic archipelago of svalbard were investigated. abundance, biovolume, and community structure were evaluated by using epifluorescence microscopy and culturing methods. particular emphasis was laid on distinctions in the chemical and physical properties of the supraglacial habitats and their relation to the microbial communities, and quan ... | 2006 | 17072679 |
| protein expression profiles in an endosymbiotic cyanobacterium revealed by a proteomic approach. | molecular mechanisms behind adaptations in the cyanobacterium (nostoc sp.) to a life in endosymbiosis with plants are still not clarified, nor are the interactions between the partners. to get further insights, the proteome of a nostoc strain, freshly isolated from the symbiotic gland tissue of the angiosperm gunnera manicata linden, was analyzed and compared with the proteome of the same strain when free-living. extracted proteins were separated by two-dimensional gel electrophoresis and were i ... | 2006 | 17073307 |
| a soluble 3d lc/ms/ms proteome of the filamentous cyanobacterium nostoc punctiforme. | nostoc punctiforme is an oxygenic photoautotrophic cyanobacterium with multiple developmental states, which can form nitrogen-fixing symbioses with a variety of terrestrial plants. 3d lc/ms/ms shotgun peptide sequencing was used to analyze the proteome when n. punctiforme is grown in continuous moderate light with ammonia as the nitrogen source. the soluble proteome includes 1575 proteins, 50% of which can be assigned to core metabolic and transport functions. another 39% are assigned to protein ... | 2006 | 17081061 |
| functional and phylogenetic properties of the pore-forming beta-barrel transporters of the omp85 family. | beta-barrel-shaped channels of the omp85 family are involved in the translocation or assembly of proteins of bacterial, mitochondrial, and plastidic outer membranes. we have compared these proteins to understand the evolutionary development of the translocators. we have demonstrated that the proteins from proteobacteria and mitochondria have a pore diameter that is at least five times smaller than found for the omp85 in cyanobacteria and plastids. this finding can explain why omp85 from cyanobac ... | 2007 | 17088246 |
| characterization of the nitrate-nitrite transporter of the major facilitator superfamily (the nrtp gene product) from the cyanobacterium nostoc punctiforme strain atcc 29133. | the products of the npr1527 and npr1526 genes of the filamentous, diazotrophic, fresh-water cyanobacterium nostoc punctiforme strain atcc 29133 were identified as a nitrate transporter (nrt) and nitrate reductase (nr) respectively, by complementation of nitrate assimilation mutants of the cyanobacterium synechococcus elongatus strain pcc 7942. while other fresh-water cyanobacteria, including s. elongatus, have an atp-binding cassette (abc)-type nrt, the nrt of n. punctiforme belongs to the major ... | 2006 | 17090931 |
| the atypical iron-coordination geometry of cytochrome f remains unchanged upon binding to plastocyanin, as inferred by xas. | the transient complex between cytochrome f and plastocyanin from the cyanobacterium nostoc sp. pcc 7119 has been analysed by x-ray absorption spectroscopy in solution, using both proteins in their oxidized and reduced states. fe k-edge data mainly shows that the atypical metal coordination geometry of cytochrome f, in which the n-terminal amino acid acts as an axial ligand of the heme group, remains unaltered upon binding to its redox partner, plastocyanin. this fact suggests that cytochrome f p ... | 2006 | 17111237 |
| studies on poly-beta-hydroxybutyrate synthase activity of nostoc muscorum. | this study compares the phb synthase activity of nostoc muscorum, a n(2)-fixing cyanobacterium under control (grown in usual bg-11 medium), nitrogen (n) and phosphorus (p) deprivation and chemoheterotrophic conditions. specific activity of phb synthase did not depict significant variations in the latter three types of cultures, except for the control one, where a significantly lower activity was recorded. phb synthase activity was detected only in the soluble fractions of both the control as wel ... | 2006 | 17116969 |
| a bacterial dynamin-like protein. | dynamins form a superfamily of large mechano-chemical gtpases that includes the classical dynamins and dynamin-like proteins (dlps). they are found throughout the eukarya, functioning in core cellular processes such as endocytosis and organelle division. many bacteria are predicted by sequence to possess large gtpases with the same multidomain architecture that is found in dlps. mechanistic dissection of dynamin family members has been impeded by a lack of high-resolution structural data current ... | 2006 | 17122778 |
| high photobiological hydrogen production activity of a nostoc sp. pcc 7422 uptake hydrogenase-deficient mutant with high nitrogenase activity. | we describe a strategy to establish cyanobacterial strains with high levels of h(2) production that involves the identification of promising wild-type strains followed by optimization of the selected strains using genetic engineering. nostoc sp. pcc 7422 was chosen from 12 other heterocystous strains, because it has the highest nitrogenase activity. we sequenced the uptake hydrogenase (hup) gene cluster as well as the bidirectional hydrogenase gene cluster from the strain, and constructed a muta ... | 2007 | 17131047 |
| rare group i intron with insertion sequence element in a bacterial ribonucleotide reductase gene. | a rare group i intron in a cyanobacterial ribonucleotide reductase gene has been characterized. it contains a mobile insertion sequence element not required for rna splicing. ribonucleotide reductase genes were found to be hot spots for all three types of self-splicing intervening sequences, including group i and ii introns and inteins. | 2007 | 17172330 |
| peptide macrocyclization: the reductase of the nostocyclopeptide synthetase triggers the self-assembly of a macrocyclic imine. | many biologically active natural products have macrocyclic structures. in nonribosomal peptides macrocyclization is commonly achieved via the formation of intramolecular ester or amide bond catalyzed by thioesterase domains during biosynthesis. a unique and so far unknown type of peptide cyclization occurs in the nostocyclopeptide, a macrocyclic imine produced by the terrestrial cyanobacterium nostoc sp. atcc53789. in this work we show that a c-terminal reductase domain of the nostocyclopeptide ... | 2006 | 17177378 |
| trans protein splicing of cyanobacterial split inteins in endogenous and exogenous combinations. | inteins are autocatalytic protein domains that post-translationally excise from protein precursors and ligate their flanking regions with a peptide bond, in a process called protein splicing. intein-containing dna polymerases of cyanobacteria and nanoarchaea are naturally split into two separate genes at their intein domain. such naturally occurring split inteins rapidly self-associate and reconstitute protein-splicing activity in trans. here, we analyze the in vitro protein-splicing activity of ... | 2007 | 17198403 |
| carbon cycling in anabaena sp. pcc 7120. sucrose synthesis in the heterocysts and possible role in nitrogen fixation. | nitrogen (n) available to plants mostly originates from n(2) fixation carried out by prokaryotes. certain cyanobacterial species contribute to this energetically expensive process related to carbon (c) metabolism. several filamentous strains differentiate heterocysts, specialized n(2)-fixing cells. to understand how c and n metabolism are regulated in photodiazotrophically grown organisms, we investigated the role of sucrose (suc) biosynthesis in n(2) fixation in anabaena sp. pcc 7120 (also know ... | 2007 | 17237189 |
| biosynthetic characterization and chemoenzymatic assembly of the cryptophycins. potent anticancer agents from cyanobionts. | the lichen cyanobacterial symbiont nostoc sp. atcc 53789 and its close relative nostoc sp. gsv 224 are prolific producers of natural products, generating >25 derivatives of the cryptophycin class of secondary metabolites. cryptophycin 1, the prototypic member of the class, is a potent tubulin-depolymerizing agent, and several semisynthetic derivatives are being developed as anticancer therapeutics. here we provide a detailed characterization of the cryptophycin metabolic pathway by stable-isotop ... | 2006 | 17240975 |
| the specificity in the interaction between cytochrome f and plastocyanin from the cyanobacterium nostoc sp. pcc 7119 is mainly determined by the copper protein. | the plastocyanin-cytochrome f complex from nostoc exhibits relevant structural differences when compared with the homologous complexes from other cyanobacteria and plants, with electrostatic and hydrophobic interactions being differently involved in each case. here, five negatively charged residues of a recombinant form of cytochrome f from nostoc have been replaced with either neutral or positively charged residues, and the effects of mutations on the kinetics of electron transfer to wild-type ... | 2007 | 17240983 |
| discovery of two cyanobacterial phenylalanine ammonia lyases: kinetic and structural characterization. | phenylalanine ammonia lyase (pal) catalyzes the deamination of phenylalanine to cinnamate and ammonia. while pals are common in terrestrial plants where they catalyze the first committed step in the formation of phenylpropanoids, only a few prokaryotic pals have been identified to date. here we describe for the first time pals from cyanobacteria, in particular, anabaena variabilis atcc 29413 and nostoc punctiforme atcc 29133, identified by screening the genome sequences of these organisms for me ... | 2007 | 17240984 |
| allosteric activation by dimerization of the pknd receptor ser/thr protein kinase from mycobacterium tuberculosis. | to define how extracellular signals activate bacterial receptor ser/thr protein kinases, we characterized the regulatory functions of a weak dimer interface identified in the mycobacterium tuberculosis pknb and pkne receptor kinases. sequence comparisons revealed that the analogous interface is conserved in pknd orthologs from diverse bacterial species. to analyze the roles of dimerization, we constructed m. tuberculosis pknd kinase domain (kd) fusion proteins that formed dimers upon addition of ... | 2007 | 17242402 |
| high cyanobiont selectivity of epiphytic lichens in old growth boreal forest of finland. | here, cyanobiont selectivity of epiphytic lichen species was examined in an old growth forest area in finland. samples of the eight lichen species were collected from the same aspen (populus tremula) and adjacent aspens in the same stand. the cyanobionts of these samples were compared with free and symbiotic nostoc obtained from other habitats and geographic regions. our results, based on the phylogenetic analysis of a partial small subunit of the ribosomal dna (16s rdna) and the rbclx gene comp ... | 2007 | 17244057 |
| effects of three pesticides on the growth, photosynthesis and photoinhibition of the edible cyanobacterium ge-xian-mi (nostoc). | effects of butachlor, bensulfuron-methyl, and dimethoate on the growth, photosynthesis, and photoinhibition of the edible cyanobacterium ge-xian-mi were examined in order to gain insight into the relationship between its productivity reduction and the abusive use of pesticides in the field. severe inhibition of growth was found in the presence of four- to six-fold field concentration of butachlor and very high concentrations of bensulfuron-methyl and dimethoate. mild stimulation of photosynthesi ... | 2007 | 17258325 |
| proteomic analyses of the photoauto- and diazotrophically grown cyanobacterium nostoc sp. pcc 73102. | the filamentous cyanobacteria of the genus nostoc are globally distributed, phenotypically complex organisms, capable of cellular differentiation and of forming symbiotic associations with a wide range of plants. to further our understanding of these processes and functions, the proteome of photoautotrophically and diazotrophically grown nostoc sp. pcc 73102 (n. punctiforme) cells was examined. extracted proteins were separated into membrane and soluble protein fractions and analysed using two-d ... | 2007 | 17259633 |
| an itraq-based quantitative analysis to elaborate the proteomic response of nostoc sp. pcc 7120 under n2 fixing conditions. | nostoc sp. pcc 7120 is an oxygen-evolving photoautotrophic n2 fixing filamentous cyanobacterium. upon nitrogen starvation, a range of processes are initiated, such as differentiation of the heterocysts, specific cells where n2 fixation takes place. we have characterized and quantified the proteome of the nostoc sp. pcc 7120 wild-type strain grown under n2 fixing and non-n2 fixing conditions. to assess global proteome changes in response to environmental changes, measurements were made using the ... | 2007 | 17269719 |
| insight into the radical mechanism of phycocyanobilin-ferredoxin oxidoreductase (pcya) revealed by x-ray crystallography and biochemical measurements. | the x-ray crystal structure of the substrate-free form of phycocyanobilin (pcb)-ferredoxin oxidoreductase (pcya; ec 1.3.7.5) from the cyanobacterium nostoc sp. pcc7120 has been solved at 2.5 a resolution. a comparative analysis of this structure with those recently reported for substrate-bound and substrate-free forms of pcya from the cyanobacterium synechocystis sp. pcc6803 (hagiwara et al. (2006) proc. natl. acad. sci. u.s.a. 103, 27-32; hagiwara et al. (2006) febs lett. 580, 3823-3828) provid ... | 2007 | 17279614 |
| carbamidocyclophanes a-e, chlorinated paracyclophanes with cytotoxic and antibiotic activity from the vietnamese cyanobacterium nostoc sp. | five new paracyclophanes, carbamidocyclophanes a-e (1-5), characterized by carbamido side chains at a symmetric [7.7]paracyclophane ring, have been isolated from the biomass of the vietnamese nostoc sp. cavn 10. structure elucidation by spectroscopic methods showed that 1-5 vary in the substitution pattern of the chlorinated butyl side chains. the compounds exhibited cytotoxic activity against mcf-7 (breast cancer cell line) and fl cells (human amniotic epithelial cell line) and moderate antibac ... | 2007 | 17311455 |
| mutations stabilize small subunit ribosomal rna in desiccation-tolerant cyanobacteria nostoc. | the ribosomal rna molecule is an ideal model for evaluating the stability of a gene product under desiccation stress. we isolated 8 nostoc strains that had the capacity to withstand desiccation in habitats and sequenced their 16s rrna genes. the stabilities of 16s rrnas secondary structures, indicated by free energy change of folding, were compared among nostoc and other related species. the results suggested that 16s rrna secondary structures of the desiccation-tolerant nostoc strains were more ... | 2007 | 17334839 |
| cofactor regeneration in phototrophic cyanobacteria applied for asymmetric reduction of ketones. | the obligate photoautotrophic cyanobacterium synechococcus pcc7942 and the photoheterotrophic heterocystous cyanobacterium noctoc muscorum are able to reduce prochiral ketones asymmetrically to optical pure chiral alcohols without light. an example is the synthesis of s-pentafluoro(phenyl-)ethanol with an enantiomeric excess >99% if 2'-3'-4'-5'-6'-pentafluoroacetophenone is used as substrate. if no light is available for regeneration of the cofactor nicotinamide adenine dinucleotide phosphate (r ... | 2007 | 17345080 |
| fura modulates gene expression of alr3808, a dpsa homologue in nostoc (anabaena) sp. pcc7120. | the dna-binding protein from stationary phase (dps) protein family plays an important role in protecting microorganisms from oxidative and nutritional stresses. in silico analysis of the promoter region of alr3808, a dpsa homologue from the cyanobacterium nostoc sp. pcc7120 shows putative iron-boxes with high homology with those recognized by fura (ferric uptake regulator). evidence for the modulation of dpsa by fura was obtained using in vitro and in vivo approaches. selex linked to pcr was use ... | 2007 | 17350003 |
| molecular genetics and genomic analysis of scytonemin biosynthesis in nostoc punctiforme atcc 29133. | the indole-alkaloid scytonemin is the most common and widespread sunscreen among cyanobacteria. previous research has focused on its nature, distribution, ecology, physiology, and biochemistry, but its molecular genetics have not been explored. in this study, a scytonemin-deficient mutant of the cyanobacterium nostoc punctiforme atcc 29133 was obtained by random transposon insertion into open reading frame npr1273. the absence of scytonemin under conditions of induction by uv irradiation was the ... | 2007 | 17351042 |
| cloning of lipoxygenase genes from a cyanobacterium, nostoc punctiforme, and its expression in eschelichia coli. | oxylipin metabolism represents one of the important hormonal and defensive mechanisms employed by plants, algae, or animals. it begins mostly with the reaction of lipoxygenases (loxs), which catalyze the oxygenation of polyunsaturated fatty acids to form the corresponding hydroperoxides. at present, little information about loxs in cyanobacteria has been reported. herein, we report the first isolation of two lox genes (nplox1 and nplox2) from a cyanobacterium, nostoc punctiforme atcc29133. incub ... | 2007 | 17375360 |
| group 3 sigma factor gene, sigj, a key regulator of desiccation tolerance, regulates the synthesis of extracellular polysaccharide in cyanobacterium anabaena sp. strain pcc 7120. | the changes in the expression of sigma factor genes during dehydration in terrestrial nostoc hk-01 and aquatic anabaena pcc 7120 were determined. the expression of the sigj gene in terrestrial nostoc hk-01, which is homologous to sigj (alr0277) in aquatic anabaena pcc 7120, was significantly induced in the mid-stage of dehydration. we constructed a higher-expressing transformant of the sigj gene (he0277) in anabaena pcc 7120, and the transformant acquired desiccation tolerance. the results of an ... | 2007 | 17376888 |
| three distinct clades of cultured heterocystous cyanobacteria constitute the dominant n2-fixing members of biological soil crusts of the colorado plateau, usa. | the identity of the numerically dominant n(2)-fixing bacteria in biological soil crusts of the colorado plateau region and two outlying areas was determined using multiple approaches, to link the environmental diversity of nifh gene sequences to cultured bacterial isolates from the regions. of the nifh sequence-types detected in soil crusts of the colorado plateau, 89% (421/473) were most closely related to nifh signature sequences from cyanobacteria of the order nostocales. n(2)-fixing cyanobac ... | 2007 | 17381526 |
| structural characterization of the fusion of two pentapeptide repeat proteins, np275 and np276, from nostoc punctiforme: resurrection of an ancestral protein. | the nostoc punctiforme genes np275 and np276 are two adjacently encoded proteins of 98 and 75 amino acids in length and exhibit sequences composed of tandem pentapeptide repeats. the structures of np275 and a fusion of np275 and np276 were determined to 2.1 and 1.5 a, respectively. the two nostoc proteins fold as highly symmetric right-handed quadrilateral beta-helices similar to the mycobacterial protein mfpa implicated in fluoroquinolone resistance and dna gyrase inhibition. the sequence compo ... | 2007 | 17384236 |
| anti-proliferative effects of recombinant iron superoxide dismutase on hepg2 cells via a redox-dependent pi3k/akt pathway. | the coding sequence for an iron superoxide dismutase (fe-sod) was amplified from the nostoc commune genome. recombinant fe-sod was overexpressed in escherichia coli, accounting for approximately 76% of total bacterial protein. fe-sod was purified from bacterial lysate by ni-nta column chromatography and used to generate an anti-sod antibody. the purified fe-sod was encapsulated in liposomes and delivered to hepg2 liver tumor cells to eliminate cellular superoxide anions. the sod-loaded cells exh ... | 2007 | 17387468 |
| biosorption of cr(vi) by immobilized biomass of two indigenous strains of cyanobacteria isolated from metal contaminated soil. | biosorption of cr(vi) using native strains of cyanobacteria from metal contaminated soil in the premises of textile mill has been reported in this paper. biosorption was studied as a function of ph (1-5), contact time (5-180 min) and initial chromium ion concentration (5-20mg/l) to find out the maximum biosorption capacity of alginate immobilized nostoc calcicola hh-12 and chroococcus sp. hh-11. the optimum conditions for cr(vi) biosorption are almost same for the two strains (ph 3-4, contact ti ... | 2007 | 17403568 |
| m. tuberculosis ser/thr protein kinase d phosphorylates an anti-anti-sigma factor homolog. | receptor ser/thr protein kinases are candidates for sensors that govern developmental changes and disease processes of mycobacterium tuberculosis (mtb), but the functions of these kinases are not established. here, we show that mtb protein kinase (pkn) d overexpression alters transcription of numerous bacterial genes, including rv0516c, a putative anti-anti-sigma factor, and genes regulated by sigma factor f. the pknd kinase domain directly phosphorylated rv0516c, but no other sigma factor regul ... | 2007 | 17411339 |
| oxylipin formation in nostoc punctiforme (pcc73102). | the dioxygenation of polyunsaturated fatty acids is mainly catalyzed by members of the lipoxygenase enzyme family in flowering plants and mosses. lipoxygenase products can be metabolized further and are known as signalling substances that play a role in plant development as well as in plant responses to wounding and pathogen attack. apart from accumulating data in mammals, flowering and non-flowering plants, information on the relevance of lipid peroxide metabolism in prokaryotic organisms is sc ... | 2007 | 17412376 |
| molecular analysis of genes in nostoc punctiforme involved in pilus biogenesis and plant infection. | hormogonia are the infective agents in many cyanobacterium-plant symbioses. pilus-like appendages are expressed on the hormogonium surface, and mutations in pil-like genes altered surface piliation and reduced symbiotic competency. this is the first molecular evidence that pilus biogenesis in a filamentous cyanobacterium requires a type iv pilus system. | 2007 | 17416648 |
| the anabaena sp. strain pcc 7120 asr1734 gene encodes a negative regulator of heterocyst development. | the novel asr1734 gene of anabaena (nostoc) sp. strain pcc 7120 inhibited heterocyst development when present in extra copies. overexpression of asr1734 inhibited heterocyst development in several strains including the wild type and two strains that form multiple contiguous heterocysts (mch phenotype): a pats null mutant and a hetr(r223w) mutant. overexpression of asr1734 also caused increased nbla messenger rna levels, and increased loss of autofluorescence in vegetative cells throughout filame ... | 2007 | 17462023 |
| global gene expression patterns of nostoc punctiforme in steady-state dinitrogen-grown heterocyst-containing cultures and at single time points during the differentiation of akinetes and hormogonia. | the vegetative cells of the filamentous cyanobacterium nostoc punctiforme can differentiate into three mutually exclusive cell types: nitrogen-fixing heterocysts, spore-like akinetes, and motile hormogomium filaments. a dna microarray consisting of 6,893 n. punctiforme genes was used to identify the global transcription patterns at single time points in the three developmental states, compared to those in ammonium-grown time zero cultures. analysis of ammonium-grown cultures yielded a transcript ... | 2007 | 17483217 |
| reconstitution of modular pdk1 functions on trans-splicing of the regulatory ph and catalytic kinase domains. | the serine-threonine protein kinases pdk1 and pkb each contain a pleckstrin homology (ph) domain that binds the membrane-bound phosphatidylinositol 3,4,5-triphosphate [pi(3,4,5)p3] second messenger and is required for pdk1-catalyzed phosphorylation and activation of pkb. while x-ray structures have been reported for the individual regulatory ph and catalytic kinase domain constructs of both pdk1 and pkb, diffraction quality crystals of full length constructs have yet to be obtained, likely due t ... | 2007 | 17500509 |
| effects of periodic desiccation on the synthesis of the uv-screening compound, scytonemin, in cyanobacteria. | scytonemin is an ultraviolet radiation (uvr)-screening compound synthesized by some sheathed cyanobacteria exposed to high solar and sky radiation. it is primarily produced in response to uva radiation, but certain environmental stresses can enhance synthesis. this study focuses on the effects of periodic desiccation on scytonemin synthesis in three desiccation-tolerant cyanobacterial strains, nostoc punctiforme pcc 73102, chroococcidiopsis ccmee 5056 and chroococcidiopsis ccmee 246. nostoc punc ... | 2007 | 17504482 |
| l-amino acid oxidases with specificity for basic l-amino acids in cyanobacteria. | the two closely related fresh water cyanobacteria synechococcus elongatus pcc 6301 and synechococcus elongatus pcc 7942 have previously been shown to constitutively express a fad-containing l-amino acid oxidase with high specificity for basic l-amino acids (l-arginine being the best substrate). in this paper we show that such an enzyme is also present in the fresh water cyanobacterium synechococcus cedrorum pcc 6908. in addition, an improved evaluation of the nucleotide/amino acid sequence of th ... | 2007 | 17542496 |
| purification and characterization of corrinoid-compounds from the dried powder of an edible cyanobacterium, nostoc commune (ishikurage). | vitamin b12 content (98.8 +/- 5.6 microg/100 g dry weight) of an edible cyanobacterium, nostoc commune (ishikurage) was determined by the lactobacillus delbrueckii atcc 7830 microbiological method. bioautography with vitamin b12-dependent escherichia coli 215 indicated that n. commune contained two (main and minor) corrinoid-compounds. these corrinoid-compounds were purified to homogeneity from the dried algal cells and characterized. the main and minor purified corrinoid-compounds were identifi ... | 2007 | 17616007 |
| transcription and regulation of the bidirectional hydrogenase in the cyanobacterium nostoc sp. strain pcc 7120. | the filamentous, heterocystous cyanobacterium nostoc sp. strain pcc 7120 (anabaena sp. strain pcc 7120) possesses an uptake hydrogenase and a bidirectional enzyme, the latter being capable of catalyzing both h2 production and evolution. the completely sequenced genome of nostoc sp. strain pcc 7120 reveals that the five structural genes encoding the bidirectional hydrogenase (hoxefuyh) are separated in two clusters at a distance of approximately 8.8 kb. the transcription of the hox genes was exam ... | 2007 | 17630298 |
| desensitization of soluble guanylyl cyclase, the no receptor, by s-nitrosylation. | the molecular mechanism of desensitization of soluble guanylyl cyclase (sgc), the no receptor, has long remained unresolved. posttranslational modification and redox state have been postulated to affect sgc sensitivity to no but evidence has been lacking. we now show that sgc can be s-nitrosylated in primary aortic smooth muscle cells by s-nitrosocysteine (csno), an s-nitrosylating agent, in human umbilical vein endothelial cells after vascular endothelial growth factor treatment and in isolated ... | 2007 | 17636120 |
| anti-herpes simplex virus target of an acidic polysaccharide, nostoflan, from the edible blue-green alga nostoc flagelliforme. | the acidic polysaccharide nostoflan was previously isolated as an antiviral component from the terrestrial alga nostoc flagelliforme. in the present study, we examined the target for its anti-herpes simplex virus type 1 action. in time-of-addition experiments, the most sensitive stage of viral replication to nostoflan was found to be early events, including the virus binding and/or penetration processes. in order to determine what extent nostoflan may be involved in these processes, virus bindin ... | 2007 | 17666824 |
| nanoscale visualization of a fibrillar array in the cell wall of filamentous cyanobacteria and its implications for gliding motility. | many filamentous cyanobacteria are motile by gliding, which requires attachment to a surface. there are two main theories to explain the mechanism of gliding. according to the first, the filament is pushed forward by small waves that pass along the cell surface. in the second, gliding is powered by the extrusion of slime through pores surrounding each cell septum. we have previously shown that the cell walls of several motile cyanobacteria possess an array of parallel fibrils between the peptido ... | 2007 | 17693519 |
| desaturase genes in a psychrotolerant nostoc sp. are constitutively expressed at low temperature. | antarctic psychrotolerant, nostoc sp. (so-36), when grown at 25 degrees c and then shifted to 10 degrees c, showed an increase in the tri-unsaturated fatty acid [c(18:3(9,12,15))] at the expense of mono- [c(18:1(9))] and di-unsaturated [c(18:2(9,12))] fatty acids. these results indicate that the activities of the enzymes desa and desb are up-regulated, when cultures were grown at 10 degrees c or shifted to 10 degrees c from 25 degrees c. however, rt-pcr studies indicated a constitutive expressio ... | 2007 | 17697671 |
| gas vacuole development in a blue-green alga. | de novo productioni of gas vacutoles can be induced in the blue-green alga nostoc muscorum by transferring the cells from a defined medium to distilled water. the unusual ultrastructure of the gas vacuole membranes permits their easy recognition when specimens are prepared for electron microscopy by freeze-etching. the youngest gas vacuoles are biconical organelles; 48 hours after induction the gas vacuoles reach their miaximum observed length when they are cylinders (1.5 by 0.1 micro) with corn ... | 1969 | 17807814 |
| algae: nitrogen fixation by antarctic species. | algae from terrestrial and fresh-water habitats in antarctica were examined for ability to fix atmospheric nitrogen. nostoc commune was the only species capable of growing in nitrogen-free medium; nitrogen fixation by this species was verified by assimilation of n(15). the importance of nitrogen-fixing algae to terrestrial life in the antarctic is discussed. | 1963 | 17812987 |
| identification and expression analyses of putative sesquiterpene synthase genes in phormidium sp. and prevalence of geoa-like genes in a drinking water reservoir. | the occurrence of taste and odor problems in drinking water supplies is a widespread phenomenon. from a saxonian water reservoir we isolated a cyanobacterial species which was classified as phormidium sp. under laboratory conditions it produced an earthy-musty smell due to the synthesis of geosmin. the only genes shown to be involved in geosmin biosynthesis are cyc2 and geoa of streptomyces. based on the alignment of cyc2 with a putative sesquiterpene synthase of nostoc punctiforme, a degenerate ... | 2007 | 17827321 |
| action spectrum for developmental photo-induction of the blue-green alga nostoc muscorum. | the dark-grown cyanophyte requires a brief exposure to light from the 650 mmicro region of the spectrum before it can complete its developmental cycle. induction is reversed by exposure to green light. a blue protein, presumably allophycocyanin (absorption maximum, 650 mmicro) has been demonstrated in aqueous extracts of the cyanophycean cells. | 1962 | 17836542 |
| lyase activities of cpcs- and cpct-like proteins from nostoc pcc7120 and sequential reconstitution of binding sites of phycoerythrocyanin and phycocyanin beta-subunits. | genes all5292 (cpcs2) and alr0617 (cpcs1) in the cyanobacterium nostoc pcc7120 are homologous to the biliprotein lyase cpcs, and genes all5339 (cpct1) and alr0647 (cpct2) are homologous to the lyase cpct. the functions of the encoded proteins were screened in vitro and in a heterologous escherichia coli system with plasmids conferring biosynthesis of the phycocyanobilin chromophore and of the acceptor proteins beta-phycoerythrocyanin (pecb) or beta-phycocyanin (cpcb). cpct1 is a regioselective b ... | 2007 | 17895251 |
| recurrent adenylation domain replacement in the microcystin synthetase gene cluster. | microcystins are small cyclic heptapeptide toxins produced by a range of distantly related cyanobacteria. microcystins are synthesized on large nrps-pks enzyme complexes. many structural variants of microcystins are produced simultaneously. a recombination event between the first module of mcyb (mcyb1) and mcyc in the microcystin synthetase gene cluster is linked to the simultaneous production of microcystin variants in strains of the genus microcystis. | 2007 | 17908306 |
| cross-talk between iron and nitrogen regulatory networks in anabaena (nostoc) sp. pcc 7120: identification of overlapping genes in fura and ntca regulons. | nitrogen signalling in cyanobacteria involves a complex network in which the availability of iron plays an important role. in the nitrogen-fixing cyanobacterium anabaena sp. pcc 7120, iron uptake is controlled by fura, while ntca is the master regulator of nitrogen metabolism and shows a mutual dependence with hetr in the first steps of heterocyst development. expression of fura is modulated by ntca and it is enhanced in a hetr(-) background. iron starvation in cells grown in the presence of com ... | 2007 | 17920076 |
| effects of disruption of homocitrate synthase genes on nostoc sp. strain pcc 7120 photobiological hydrogen production and nitrogenase. | in the case of nitrogenase-based photobiological hydrogen production systems of cyanobacteria, the inactivation of uptake hydrogenase (hup) leads to significant increases in hydrogen production activity. however, the high-level-activity stage of the hup mutants lasts only a few tens of hours under air, a circumstance which seems to be caused by sufficient amounts of combined nitrogen supplied by active nitrogenase. the catalytic femo cofactor of nitrogenase binds homocitrate, which is required f ... | 2007 | 17933939 |
| structural and functional characterization of galactooligosaccharides in nostoc commune: beta-d-galactofuranosyl-(1-->6)-[beta-d-galactofuranosyl-(1-->6)]2-beta-d-1,4-anhydrogalactitol and beta-(1-->6)-galactofuranosylated homologues. | a new class of galactooligosaccharides has been identified from the terrestrial cyanobacterium nostoc commune by ms and nmr techniques. these consist of beta-d-galactofuranosyl-(1-->6)-[beta-d-galactofuranosyl-(1-->6)]n-beta-d-1,4-anhydrogalactitols with n ranging from 2 to 8, corresponding to compounds designated 1 through 7. in total these saccharides amounted to approximately 0.35% of the dry thallus of n. commune, while in several other cyanobacteria they were not detected. possibly they pla ... | 2007 | 17935705 |
| yest: a new rhamnogalacturonan acetyl esterase from bacillus subtilis. | yest, a putative protein from bacillus subtilis atcc 6633 that has been provisionally classified as a rhamnogalacturonan acetyl esterase (rgae) in ce-12 family, was cloned, expressed in escherichiacoli rosetta (de3), and purified. the enzyme is monomeric with a molecular mass of 37 kda and presents thermophilic properties similar to rgae from aspergillus aculeatus, although yest is more alkaliphilic. the study of inhibitors confirmed the importance of the his and the nucleophilic ser for the est ... | 2008 | 17957779 |
| free radical scavenging and antioxidant enzymes activation of polysaccharide extract from nostoc sphaeroides. | nostoc sphaeroides kuetzing has been used as a traditional medicine in china to treat a variety of ailments. this research identified the antioxidant activities of polysaccharide extract from nostoc sphaeroides. the extract, which contains 46.2% carbohydrates, exhibited an effective scavenging capability on superoxide radical, hydroxyl radicals in non site-specific as well as site-specific assays, and also performed lipid peroxidation inhibition in a dose-dependent manner. polysaccharide extract ... | 2007 | 17963327 |
| effect of uv-b and high visual radiation on photosynthesis in freshwater (nostoc spongiaeforme) and marine (phormidium corium) cyanobacteria. | human activity is causing depletion of ozone in stratosphere, resulting in increased uv-b radiation and global warming. however, impact of these climatic changes on the aquatic organism (especially marine) is not fully understood. here, we have studied the effect of excess uv-b and visible radiation on photosynthetic pigments, fatty acids content, lipid peroxidation, nitrogen content, nitrogen reductase activity and membrane proteins, induction of mycosporine-like amino acids (maas) and antioxid ... | 2007 | 17970281 |
| pas-mediated dimerization of soluble guanylyl cyclase revealed by signal transduction histidine kinase domain crystal structure. | signal transduction histidine kinases (sthk) are key for sensing environmental stresses, crucial for cell survival, and attain their sensing ability using small molecule binding domains. the n-terminal domain in an sthk from nostoc punctiforme is of unknown function yet is homologous to the central region in soluble guanylyl cyclase (sgc), the main receptor for nitric oxide (no). this domain is termed h-noxa (or h-noba) because it is often associated with the heme-nitric oxide/oxygen binding (h- ... | 2008 | 18006497 |
| a lipoxygenase with linoleate diol synthase activity from nostoc sp. pcc 7120. | the dioxygenation of pufas (polyunsaturated fatty acids) in plants is mainly catalysed by members of the lox (lipoxygenase) enzyme family. lox products may be further metabolized, and are known as signalling substances in plant development and in responses to wounding and pathogen attack. in contrast with the situation in eukaryotes, information on the relevance of lipid peroxide metabolism in prokaryotic organisms is scarce. therefore, we aimed to analyse loxs and oxylipin patterns of cyanobact ... | 2008 | 18031288 |
| nezha, a novel active miniature inverted-repeat transposable element in cyanobacteria. | miniature inverted-repeat transposable elements (mites) were first identified in plants and exerted extensive proliferations throughout eukaryotic and archaeal genomes. but very few mites have been characterized in bacteria. we identified a novel mite, called nezha, in cyanobacteria anabaena variabilis atcc 29413 and nostoc sp. pcc 7120. nezha, like most previously known mites in other organisms, is small in size, non-coding, carrying tir and dr signals, and of potential to form a stable rna sec ... | 2008 | 18035045 |
| a gene cluster that regulates both heterocyst differentiation and pattern formation in anabaena sp. strain pcc 7120. | wild-type anabaena sp. strain pcc 7120, a filamentous nitrogen-fixing cyanobacterium, produces single heterocysts at semi-regular intervals. asr0100 (patu5) and alr0101 (patu3) are homologous to the 5' and 3' portions of patu of nostoc punctiforme. alr0099 (hetz) overlaps the 5' end of patu5. hetz, patu5 and patu3 were all upregulated, or expressed specifically, in proheterocysts and heterocysts. mutants of hetz showed delayed or no heterocyst differentiation. in contrast, a patu3 mutation produ ... | 2007 | 18045384 |
| sorption and desorption studies of chromium(vi) from nonviable cyanobacterium nostoc muscorum biomass. | this communication presents results pertaining to the sorptive and desorptive studies carried out on chromium(vi) removal onto nonviable freshwater cyanobacterium (nostoc muscorum) biomass. influence of varying the conditions for removal of chromium(vi), such as the ph of aqueous solution, the dosage of biosorbent, the contact time with the biosorbent, the temperature for the removal of chromium, the effect of light metal ions and the adsorption-desorption studies were investigated. sorption int ... | 2008 | 18053641 |
| mutation at different sites in the nostoc punctiforme cyac gene, encoding the multiple-domain enzyme adenylate cyclase, results in different levels of infection of the host plant blasia pusilla. | the filamentous cyanobacterium nostoc punctiforme forms symbioses with plants. disruption of the catalytic domain of the n. punctiforme adenylate cyclase (cyac) significantly increased symbiotic competence, whereas reduced infectivity was observed in a mutant with a disruption close to the n terminus of cyac. the total cellular cyclic amp levels were significantly reduced in both mutants. | 2008 | 18156269 |