Publications

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
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
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
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
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
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
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
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
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
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
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
structure and development of nostoc strands in leiosporoceros dussii (anthocerotophyta): a novel symbiosis in land plants.	the presence of nostoc in longitudinally oriented schizogenous canals is a feature that separates leiosporoceros from all other hornworts and represents a novel symbiotic arrangement in land plants. in surface view, nostoc canals are visible as elongated, dichotomously branched blue-green strands. all other hornworts develop numerous discrete globose colonies through continuous production of mucilage clefts as avenues for multiple invasions within a single thallus. to elucidate the anatomy and d ...	2006	21642133
production and characterization of antimicrobial active substance from the cyanobacterium nostoc muscorum.	in this investigation, the cyanobacterium nostoc muscorum exhibited antagonistic activity against gram-positive and gram-negative bacteria and filamentous fungi. the results indicated that the active substance produced maximally after 12 days of incubation in shaken culture at 35-¦c, at ph 8.0 in bg-11 medium. the increase in nitrate concentration of the medium led to an increase in the antimicrobial production. chloroform was the best solvent for extracting the active material. the antagonistic ...	2006	21783637
commercial applications of microalgae.	the first use of microalgae by humans dates back 2000 years to the chinese, who used nostoc to survive during famine. however, microalgal biotechnology only really began to develop in the middle of the last century. nowadays, there are numerous commercial applications of microalgae. for example, (i) microalgae can be used to enhance the nutritional value of food and animal feed owing to their chemical composition, (ii) they play a crucial role in aquaculture and (iii) they can be incorporated in ...	2006	16569602
cyanobacterial response regulator pata contains a conserved n-terminal domain (patan) with an alpha-helical insertion.	the cyanobacterium anabaena (nostoc) pcc 7120 responds to starvation for nitrogen compounds by differentiating approximately every 10th cell in the filament into nitrogen-fixing cells called heterocysts. heterocyst formation is subject to complex regulation, which involves an unusual response regulator pata that contains a chey-like phosphoacceptor (receiver, rec) domain at its c-terminus. pata-like response regulators are widespread in cyanobacteria; one of them regulates phototaxis in synechoc ...	2006	16543275
molecular cloning and functional characterization of a cell-permeable superoxide dismutase targeted to lung adenocarcinoma cells. inhibition cell proliferation through the akt/p27kip1 pathway.	in clinical oncology, many trials with superoxide dismutase (sod) have failed to demonstrate antitumor ability and in many cases even caused deleterious effects because of low tumor-targeting ability. in the current research, the nostoc commune fe-sod coding sequence was amplified from genomic dna. in addition, the single chain variable fragment (scfv) was constructed from the cdna of an lc-1 hybridoma cell line secreting anti-lung adenocarcinoma monoclonal antibody. after modification, the sod ...	2006	16551617
highly efficient protein trans-splicing by a naturally split dnae intein from nostoc punctiforme.	protein trans-splicing by the naturally split intein of the gene dnae from nostoc punctiforme (npu dnae) was demonstrated here with non-native exteins in escherichia coli. npu dnae possesses robust trans-splicing activity with an efficiency of > 98%, which is superior to that of the dnae intein from synechocystis sp. strain pcc6803 (ssp dnae). both the n- and c-terminal parts of the split npu dnae intein can be substituted with the corresponding fragment of ssp dnae without loss of trans-splicin ...	2006	16516207
occurrence of glucosylsucrose [alpha-d-glucopyranosyl- (1-->2)-alpha-d-glucopyranosyl-(1-->2)-beta-d-fructofuranoside] and glucosylated homologues in cyanobacteria. structural properties, cellular contents and possible function as thermoprotectants.	little is known about the structure and function of oligosaccharides in cyanobacteria. in this study, a new class of saccharides from nostoc was identified by ms and nmr techniques, consisting of alpha-d-glucopyranosyl-(1-->2)-[alpha-d-glucopyranosyl-(1-->2)]n-beta-d-fructofuranosides ranging from the trisaccharide (n = 1) to decasaccharide (n = 8). in nostoc ellipsosporum the cell content of saccharides increased 10-20-fold after heat stress (1 day, 40 degrees c) or during prolonged cultivation ...	2006	16367754
phytochelatin synthase, papain's cousin, in stereo.		2006	16407124
a mannan binding lectin is involved in cell-cell attachment in a toxic strain of microcystis aeruginosa.	microcystin, a hepatotoxin that represents a serious health risk for humans and livestock, is produced by the bloom-forming cyanobacterium microcystis aeruginosa in freshwater bodies worldwide. here we describe the discovery of a lectin, microvirin (mvn), in m. aeruginosa pcc7806 that shares 33% identity with the potent anti-hiv protein cyanovirin-n from nostoc ellipsosporum. carbohydrate microarrays were employed to demonstrate the high specificity of the protein for high-mannose structures con ...	2006	16420359
high-light-induced changes on photosynthesis, pigments, sugars, lipids and antioxidant enzymes in freshwater (nostoc spongiaeforme) and marine (phormidium corium) cyanobacteria.	we studied the effects of high-light exposure (500 micromol m(-2) s(-1) of photosynthetic active radiation) on the cyanobacteria nostoc spongiaeforme agardh, a fresh-water alga, and phormidium corium agardh (gomont), a marine alga, with respect to photosynthesis, pigments, sugar content, lipid peroxidation, fatty acids composition, antioxidant enzymes activity and dna. it was seen that the ratio of variable fluorescence (fv) to maximum fluorescence (fm), which is indicative of photosynthetic eff ...	2006	16464127
cyanobacterial chemotaxis to extracts of host and nonhost plants.	chemotaxis may be important when forming cyanobacterial symbioses. however, knowledge of cyanobacterial attraction towards plants and factors affecting chemotaxis is limited. chemo-attraction was observed in nostoc strains 8964:3 and pcc 73102 towards exudate or crushed extract of the natural hosts gunnera manicata, cycas revoluta and blasia pusilla, and the nonhost plants trifolium repens, arabidopsis thaliana and oryza sativa. as all tested plant extracts generated chemotaxis, the possibility ...	2006	16466377
partial characterization of extracellular polysaccharides from cyanobacteria.	four cyanobacterial strains, cyanothece sp., oscillatoria sp., nostoc sp. and nostoc carneum were studied for physico-chemical characterization of extracellular polysaccharide (eps) secreted during the controlled growth condition. hydrolyzed epss showed the compositional involvement of four sugar moieties viz. mannose, glucose, xylose and ribose in varying combinations. infrared spectra of epss showed a specific absorbance of o-h stretching at 3448-3400 cm(-1), asymmetrical-symmetrical c-h stret ...	2006	16256343
sucrose synthase and rubisco expression is similarly regulated by the nitrogen source in the nitrogen-fixing cyanobacterium anabaena sp.	in higher plants and cyanobacteria, sucrose (suc) metabolism is carried out by a similar set of enzymes. the function and regulation of suc metabolism in cyanobacteria has begun to be elucidated. in strains of anabaena sp., filamentous nitrogen-fixing cyanobacteria, suc synthase (sus, ec 2.4.1.13) controls suc cell level through the cleavage of the disaccharide. the present work shows that there are two sus genes in anabaena (nostoc) sp. that are co-regulated regarding the nitrogen source; howev ...	2006	16261375
acclimation of chlorophyll a and carotenoid levels to different irradiances in four freshwater cyanobacteria.	this study investigated carotenoid and chlorophyll a (chl-a) contents under two different growth irradiances in four freshwater cyanobacterial strains. we found an increased weight ratio of zeaxanthin to chl-a after exposure to high irradiances over several days. two out of four strains showed higher zeaxanthin amounts on a biomass basis as well. it appears that cyanobacteria enhance their carotenoid pool in response to high light conditions, as increased production of other carotenoids with pho ...	2006	16325961
a conserved histidine-aspartate pair is required for exovinyl reduction of biliverdin by a cyanobacterial phycocyanobilin:ferredoxin oxidoreductase.	phycocyanobilin:ferredoxin oxidoreductase is a member of the ferredoxin-dependent bilin reductase family and catalyzes two vinyl reductions of biliverdin ixalpha to produce phycocyanobilin, the pigment precursor of both phytochrome and phycobiliprotein chromophores in cyanobacteria. atypically for ferredoxin-dependent enzymes, phycocyanobilin:ferredoxin oxidoreductase mediates direct electron transfers from reduced ferredoxin to its tetrapyrrole substrate without metal ion or organic cofactors. ...	2006	16327013
a brownian dynamics study of the interaction of phormidium cytochrome f with various cyanobacterial plastocyanins.	brownian dynamics simulations were used to study the role of electrostatic forces in the interactions of cytochrome f from the cyanobacterium phormidium laminosum with various cyanobacterial plastocyanins. both the net charge on the plastocyanin molecule and the charge configuration around h92 (h87 in higher plants) are important in determining the interactions. those plastocyanins (pcs) with a net charge more negative than -2.0, including those from synechococcus sp. pcc7942, synechocystis sp. ...	2006	16214856
molecular mechanisms in the nitrogen-fixing nostoc-bryophyte symbiosis.		2006	16623394
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
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
the cyanobacterium anabaena sp. pcc 7120 has two distinct beta-carotene ketolases: crto for echinenone and crtw for ketomyxol synthesis.	two beta-carotene ketolases, crtw and crto, are widely distributed in bacteria, although they show no significant sequence homology with each other. the cyanobacterium anabaena sp. pcc 7120 was found to have two homologous genes. in the crtw deleted mutant, myxol 2'-fucoside was present, but ketomyxol 2'-fucoside was absent. in the crto deleted mutant, beta-carotene was accumulated, and the amount of echinenone was decreased. therefore, crtw catalyzed myxol 2'-fucoside to ketomyxol 2'-fucoside, ...	2005	16242129
modulation of carbonic anhydrase activity in two nitrogen fixing cyanobacteria, nostoc calcicola and anabaena sp.	the activity of enzyme carbonic anhydrase (ca) was investigated in two diazotrophic cyanobacteria, anabaena sp. (arm 629) and nostoc calcicola, in the presence of co2/nahco3 and different inhibitors. the ca activity increased when the cells were pretreated with a high concentration of co2/nahco3 and then transferred to ambient level co2. maximum activity of ca was observed after 8 h of incubation in light on transfer of cells from high ci to ambient level co2, and was low when incubated in dark. ...	2005	16255166
different modes of interaction in cyanobacterial complexes of plastocyanin and cytochrome f.	the highly efficient electron-transfer chain in photosynthesis demonstrates a remarkable variation among organisms in the type of interactions between the soluble electron-transfer protein plastocyanin and it partner cytochrome f. the complex from the cyanobacterium nostoc sp. pcc 7119 was studied using nuclear magnetic resonance spectroscopy and compared to that of the cyanobacterium phormidium laminosum. in both systems, the main site of interaction on plastocyanin is the hydrophobic patch. ho ...	2005	15736928
conserved pore-forming regions in polypeptide-transporting proteins.	transport of solutes and polypeptides across membranes is an essential process for every cell. in the past, much focus has been placed on helical transporters. recently, the beta-barrel-shaped transporters have also attracted some attention. the members of this family are found in the outer bacterial membrane and the outer membrane of endosymbiotically derived organelles. here we analyze the features and the evolutionary development of a specified translocator family, namely the beta-barrel-shap ...	2005	15752354
a retinoic acid binding cytochrome p450: cyp120a1 from synechocystis sp. pcc 6803.	at least 35 cytochrome p450 (p450, cyp) or cytochrome p450-like genes have been identified in 10 cyanobacterial genomes yet none have been functionally characterized. cyp110 and cyp120 represent the two largest cyanobacterial p450 families with 16 and four members, respectively, identified to date. the synechocystis sp. pcc 6803 cyp120a1 protein sequence shares high degrees of conservation with cyp120a2 from trichodesmium erythraeum ims101 and cyp120b1 and cyp120c1 from nostoc punctiforme pcc 73 ...	2005	15752715
response of growth, photosynthesis and photoinhibition of the edible cyanobacterium nostoc sphaeroides colonies to thiobencarb herbicide.	effects of thiobencarb on growth, photosynthesis and photoinhibition of nostoc sphaeroides colonies were examined. thiobencarb concentrations higher than 2 mg/l led to a significant decrease in phycoerythrin, phycocyanin and allophycocyanin content, but no significant effect on chlorophyll a (chl a) content. biomass yield, protein content and photosynthetic rate were reduced only in the highest thiobencarb concentration (10 mg/l). colonies exposed to high thiobencarb dose (10 mg/l) were more sen ...	2005	15788179
role of the surface charges d72 and k8 in the function and structural stability of the cytochrome c from nostoc sp. pcc 7119.	we investigated the role of electrostatic charges at positions d72 and k8 in the function and structural stability of cytochrome c6 from nostoc sp. pcc 7119 (cyt c6). a series of mutant forms was generated to span the possible combinations of charge neutralization (by mutation to alanine) and charge inversion (by mutation to lysine and aspartate, respectively) in these positions. all forms of cyt c6 were functionally characterized by laser flash absorption spectroscopy, and their stability was p ...	2005	15978038
mycobacterium tuberculosis serine/threonine kinases pknb, pknd, pkne, and pknf phosphorylate multiple fha domains.	the physiologic roles and the substrates of the mycobacterium tuberculosis (mtb) serine/threonine kinases are largely unknown. here, we report six novel interactions of pknb, pknd, pkne, and pknf with the forkhead-associated (fha) domains of rv0020c and the putative abc transporter rv1747. purified pknb and pknf kinase domains phosphorylated multiple fha-domain proteins in vitro. although they remain to be verified in vivo, these reactions suggest a web of interactions between stpks and fha doma ...	2005	15987910
a high proportion of baltic sea benthic cyanobacterial isolates contain apoptogens able to induce rapid death of isolated rat hepatocytes.	to assess the potential hepatotoxicity of benthic cyanobacteria, we isolated 41 strains from the baltic sea. the bacteria were differentially extracted with solvents of decreasing polarity. the extracts were tested for ability to induce death of primary rat hepatocytes in suspension culture. mainly morphological criteria were used to discriminate between cell death with apoptotic features (shrinkage, chromatin hypercondensation, budding) or necrotic features (swelling, loss of plasma membrane in ...	2005	15990143
distribution and evolution of multiple-step phosphorelay in prokaryotes: lateral domain recruitment involved in the formation of hybrid-type histidine kinases.	although most two-component signal transduction systems use a simple phosphotransfer pathway from one histidine kinase (hk) to one response regulator (rr), a multiple-step phosphorelay involving a phosphotransfer scheme of his-asp-his-asp was also discovered. central to this multiple-step-type signal transduction pathway are a hybrid-type hk, containing both an hk domain and an rr receiver domain in a single protein, and a histidine-containing phosphotransfer (hpt) that can exist either as a dom ...	2005	16000707
the anti-hiv cyanovirin-n domain is evolutionarily conserved and occurs as a protein module in eukaryotes.	a novel protein family homologous to the sugar-binding antiviral protein cyanovirin-n (cvn) is described. cvn, an 11-kda protein that, by binding to the high-mannose moiety of certain viral surface glycoproteins, blocks virus entry into target cells, has thus far been identified only in the cyanobacterium nostoc ellipsosporum. here we show that cvn belongs to a protein family identified by analysis of transcript sequences deriving from a gene expression profiling study conducted in the truffle t ...	2005	16003744
isolation of an antiviral polysaccharide, nostoflan, from a terrestrial cyanobacterium, nostoc flagelliforme.	a novel acidic polysaccharide, nostoflan, was isolated from a terrestrial cyanobacterium, nostoc flagelliforme. nostoflan exhibited a potent anti-herpes simplex virus type 1 (hsv-1) activity with a selectivity index (50% cytotoxic concentration/50% inhibitory concentration against viral replication) of 13,000. sugar composition and methylation analyses revealed that it was mainly composed of -->4)-d-glcp-(1-->, -->6,4)-d-glcp-(1-->, -->4)-d-galp-(1-->, -->4)-d-xylp-(1-->, d-glcap-(1-->, d-manp-( ...	2005	16038544
inhibition of several protein phosphatases by a non-covalently interacting microcystin and a novel cyanobacterial peptide, nostocyclin.	microcystins produced by cyanobacterial 'blooms' in reservoirs and lakes pose significant public health problems because they are highly toxic due to potent inhibition of protein serine/threonine phosphatases in the ppp family. a dehydrobutyrine (dhb)-containing microcystin variant [asp3, admadda5, dhb7]microcystin-htyr isolated from nostoc sp. was found to potently inhibit pp1, pp2a, ppp4 and ppp5 with ic50 values similar to those of microcystin-lr. however, in contrast to microcystin-lr, which ...	2005	16046071
heterocyst-specific excision of the anabaena sp. strain pcc 7120 hupl element requires xisc.	in nitrogen-limiting conditions, approximately 10% of the vegetative cells in filaments of the cyanobacterium anabaena (nostoc) sp. strain pcc 7120 differentiate into nitrogen-fixing heterocysts. during the late stages of heterocyst differentiation, three dna elements, each embedded within an open reading frame, are programmed to excise from the chromosome by site-specific recombination. the dna elements are named after the genes that they interrupt: nifd, fdxn, and hupl. the nifd and fdxn eleme ...	2005	16109944
nitrogen deprivation stimulates symbiotic gland development in gunnera manicata.	gunnera is the only genus of angiosperms known to host cyanobacteria and the only group of land plants that hosts cyanobacteria intracellularly. motile filaments of cyanobacteria, known as hormogonia, colonize gunnera plants through cells in the plant's specialized stem glands. it is commonly held that gunnera plants always possess functional glands for symbiosis. we found, however, that stem gland development did not occur when gunnera manicata plants were grown on nitrogen (n)-replete medium b ...	2005	16113217
toxicity assessment of heavy metals with nostoc muscorum l.	heavy metals in aquatic ecosystem (mn, ni, zn, cu) were tested for their toxicity against nostoc muscorum l., a common fresh water phytoplankton, with respect to chlorophyll, protein, total carbohydrate and starch contents along with growth (od). mn showed stimulatory effect up to 1.5 ppm for all the observed parameters. however, ni, zn and cu (0.1, 0.2, 0.3, 0.4 and 0.5 ppm) showed adverse effects even at 0.1 ppm. chlorophyll was most sensitive parameter followed by carbohydrate, protein and st ...	2005	16114473
laser flash-induced kinetic analysis of cytochrome f oxidation by wild-type and mutant plastocyanin from the cyanobacterium nostoc sp. pcc 7119.	oxidation of the soluble, truncated form of cytochrome f by wild-type and mutant species of plastocyanin has been analyzed by laser flash absorption spectroscopy in the cyanobacterium nostoc (formerly, anabaena) sp. pcc 7119. at low ionic strengths, the apparent electron transfer rate constant of cytochrome f oxidation by wild-type plastocyanin is 1.34 x 10(4) s(-)(1), a value much larger than those determined for the same proteins from other organisms. upon site-directed mutagenesis of specific ...	2005	16114897
the application of micro-ftir spectroscopy to analyze nutrient stress-related changes in biomass composition of phytoplankton algae.	micro-fourier transform infrared (ftir) spectroscopy was used to study changes in spectral features of three species of cyanobacteria (microcystis aeruginosa, croococcus minutus, and nostoc sp.) and two bacillariophyceae (cyclotella meneghiniana, and phaeodactylum tricornutum) in response to nutrient stress. the change of physiological state of the cells was followed during a 4-week starvation period on the basis of physiological key parameters and by means of ftir spectroscopy. changes in the i ...	2005	16122937
clustered genes required for synthesis and deposition of envelope glycolipids in anabaena sp. strain pcc 7120.	photoreduction of dinitrogen by heterocyst-forming cyanobacteria is of great importance ecologically and for subsistence rice agriculture. their heterocysts must have a glycolipid envelope layer that limits the entry of oxygen if nitrogenase is to remain active to fix dinitrogen in an oxygen-containing milieu (the fox+ phenotype). genes alr5354 (hgld), alr5355 (hglc) and alr5357 (hglb) of the filamentous cyanobacterium, anabaena sp. strain pcc 7120, and hgle of nostoc punctiforme are required fo ...	2005	16164561
cyanopeptolin 954, a chlorine-containing chymotrypsin inhibitor of microcystis aeruginosa niva cya 43.	a new depsipeptide, cyanopeptolin 954 (1), was isolated from the freshwater cyanobacterium microcystis aeruginosa niva cya 43. the structure of the compound was elucidated by chemical and spectroscopic analyses, including 2d nmr and gc-ms of the hydrolysate. the major structural differences compared to previously characterized heptadepsipeptides of microcystis are the replacement of the basic amino acid in position 4 by l-leucine, the presence of l-phenylalanine in position 6, and the uncommon r ...	2005	16180807
uv irradiation and desiccation modulate the three-dimensional extracellular matrix of nostoc commune (cyanobacteria).	cyanobacterium nostoc commune can tolerate the simultaneous stresses of desiccation, uv irradiation, and oxidation. acidic wspa, of approximately 33.6 kda, is secreted to the three-dimensional extracellular matrix and accounts for greater than 70% of the total soluble protein. the wspa gene of n. commune strain drh1 was cloned and found in a single genomic copy, in a monocistronic operon. transcription of wspa and sodf (superoxide dismutase), and synthesis and secretion of wspa, were induced upo ...	2005	16192267
competition among symbiotic cyanobacterial nostoc strains forming artificial associations with rice (oryza sativa).	competition among four symbiotically competent nostoc strains, colonizing rice roots, was examined using hetr-dgge (denaturing gradient gel electrophoresis) as strain identification. although mixed in various combinations, only one strain at a time associated with the rice roots. nostoc strain 8964:3 was the most competitive and our data suggest that its competitive fitness was dependent on rapid hormogonial spreading as displayed on agar plates. furthermore, rice roots induced hormogonia in all ...	2005	15796991
cyanobacteria from brazilian building walls are distant relatives of aquatic genera.	the 16s-rdna from 22 cyanobacteria isolated from biofilms on walls of modern and historic buildings in brazil was partially sequenced (approximately 350 bp) using specific primers. the cyanobacteria with the closest matching sequences were found using the blast tool. the sequences were combined with 52 other cyanobacterial sequences already deposited in public data banks and a dendrogram constructed, after deletion from each sequence of one of the variable 16s rdna regions (vi). the newly sequen ...	2005	15805777
comparative analysis of the two-step reaction catalyzed by prokaryotic and eukaryotic phytochelatin synthase by an ion-pair liquid chromatography assay.	genes encoding phytochelatin (pc) synthase have been found in higher plants, fission yeast and worm. recently, kinetic and mutagenic analyses of recombinant pc synthase have been revealing the molecular mechanisms underlying pc synthesis, however, a conclusive model has not been established. to clarify the mechanism of pc synthase found in eukaryotes, we have compared the two-step reactions catalyzed by the prokaryotic nostoc pc synthase (nspcs) and the eukaryotic arabidopsis pc synthase (atpcs1 ...	2005	15809863
diversity within cyanobacterial mat communities in variable salinity meltwater ponds of mcmurdo ice shelf, antarctica.	this study investigated the diversity of cyanobacterial mat communities of three meltwater ponds--fresh, orange and salt ponds, south of bratina island, mcmurdo ice shelf, antarctica. a combined morphological and genetic approach using clone libraries was used to investigate the influence of salinity on cyanobacterial diversity within these ecosystems without prior cultivation or isolation of cyanobacteria. we were able to identify 22 phylotypes belonging to phormidium sp., oscillatoria sp. and ...	2005	15816929
an nmr-based docking model for the physiological transient complex between cytochrome f and cytochrome c6.	the physiological transient complex between cytochrome f (cf) and cytochrome c(6) (cc(6)) from the cyanobacterium nostoc sp. pcc 7119 has been analysed by nmr spectroscopy. the binding constant at low ionic strength is 8 +/- 2 mm(-1), and the binding site of cc(6) for cf is localized around its exposed haem edge. on the basis of the experimental data, the resulting docking simulations suggest that cc(6) binds to cf in a fashion that is analogous to that of plastocyanin but differs between prokar ...	2005	15876432
characterization of a 4 kb variant of the nifd element in anabaena sp. strain atcc 33047.	heterocyst differentiation in some cyanobacteria is accompanied by a programmed dna rearrangement within the nitrogen fixation gene nifd. the nifd element is excised from within nifd during the latter stages of heterocyst differentiation by site-specific recombination. there is considerable variation in those nifd elements examined thus far, with nostoc sp. strain pcc 7120 and anabaena variabilis having 11 kb elements, and nostoc punctiforme having a 24 kb element. here we characterize a 4 kb ni ...	2005	15883871
benthic cyanobacteria from the baltic sea contain cytotoxic anabaena, nodularia, and nostoc strains and an apoptosis-inducing phormidium strain.	benthic cyanobacteria from aquatic environments have been reported to produce biologically active metabolites. however, the toxicity and other biological activities of benthic cyanobacteria from the baltic sea are not well known. we determined the biological activities of 21 anabaena, calothrix, nodularia, nostoc, and phormidium strains isolated from benthic littoral habitats of the baltic sea. we studied whether benthic cyanobacterial extracts caused cytotoxicity by necrosis or induced apoptosi ...	2005	15892066
the role of potassium as an ionic signal in the regulation of cyanobacterium nostoc muscorum response to salinity and osmotic stress.	spontaneously occurring thallium-resistant (tl+ -r) mutant of diazotrophic, heterocystous cyanobacterium nostoc muscorum is described in which tl+ -r phenotype is the cause of defective salinity-inducible k+ uptake activity and proline uptake activity. the results indicate that mutant strain is more sensitive to salinity and osmotic stresses than its parent. the mutational inactivation of salinity-inducible proline uptake was found associated with increased sensitivity of the cyanobacterial phot ...	2005	15900550
toxic cyanobacteria and microcystin concentrations in a public water supply reservoir in the brazilian amazonia region.	toxic cyanobacteria in public water supply reservoirs represent a serious health risk as they can release potent cyanotoxins into the water. in the present study we analyzed surface water collected from the utinga reservoir, the main source of drinking water for the city of belem-pa, in order to characterize the reservoir's cyanobacterial biota and to determine the toxicity of these organisms and the concentration of microcystins in raw and treated water. the cyanobacterial biota included potent ...	2005	15904685
characterization of a model system for the study of nostoc punctiforme akinetes.	nostoc punctiforme is a filamentous cyanobacterium that is capable of dark heterotrophy and cellular differentiation into nitrogen-fixing heterocysts, motile hormogonia, or spore-like akinetes. the study of akinete differentiation at the molecular level has been limited by the asynchronous development and limited number of akinetes formed within a filament. a system in which to study the development and genetic regulation of akinetes was investigated using a zwf mutant lacking glucose-6-phosphat ...	2005	15905999
raman spectroscopic analysis of cyanobacterial gypsum halotrophs and relevance for sulfate deposits on mars.	the raman spectra of cyanobacterial species, gloecapsa and nostoc, in clear gypsum crystals from the haughton crater, devon island, canadian high arctic, site of a meteorite impact during the miocene some 23 mya, have been recorded using several visible and near-infrared excitation wavelengths. the best spectra were obtained using a green wavelength at 514.5 nm and a confocal microscope with an image footprint of about 2 micro in diameter and 2 micro theoretical depth. raman biosignatures for be ...	2005	15912241
efficient and versatile stereoselective synthesis of cryptophycins.	the cryptophycins are a family of cyclic depsipeptides with four retrosynthetic units a to d which correspond to the respective amino acids and hydroxy acids. a new synthetic route to unit a allows the selective generation of all four stereogenic centres by introducing two of them in a catalytic asymmetric dihydroxylation, followed by substrate-controlled diastereoselective reactions. the diol also serves as the epoxide precursor. this approach provides selective access to stereoisomers of unit ...	2005	15915529
growth of cyanophage n-1 under the influence of heavy metal ions.	the growth of cyanophage n-1 in the cyanobacterium nostoc muscorum under the influence of heavy metal ions, namely co2+, cr6+, cu2+, mn2+ and ni2+ has been studied. one-step growth experiments revealed that heavy metal ions extended the latent period by 1-2 hrs with a concomitant decrease in the phage burst size. the latter was reduced in the order cu2/mn2+, ni2+, co2+ and cr6+. the treatment of the phage-infected bacteria with heavy metal ions did not induce mutations affecting either the phage ...	2005	15929395
the evolutionarily related beta-barrel polypeptide transporters from pisum sativum and nostoc pcc7120 contain two distinct functional domains.	several beta-barrel-type channels are involved in the translocation or assembly of outer membrane proteins of bacteria or endosymbiotically derived organelles. here we analyzed the functional units of the beta-barrel polypeptide transporter toc75 (translocon in outer envelope of chloroplasts) of the outer envelope of chloroplasts and of a protein, alr2269, from nostoc pcc7120 with homology to toc75, both proteins having a similar domain organization. we demonstrated that the n-terminal region fu ...	2005	15951438
three-dimensional architecture of phycobilisomes from nostoc flagelliforme revealed by single particle electron microscopy.	phycobilisomes are protein complexes that harvest light and transfer energy to the photo system. here, the three dimensional structure of intact phycobilisomes from nostoc flagelliforme is studied by a combination of negative stain electron microscopy and cryo-electron microscopy. results show that the intact phycobilisomes are composed of a tricylindrical core and six rods. each allophycocyanin cylinder presents a double-layered structure when viewed from the side and a triangular shape when vi ...	2005	15961084
respiratory cytochrome c oxidase can be efficiently reduced by the photosynthetic redox proteins cytochrome c6 and plastocyanin in cyanobacteria.	plastocyanin and cytochrome c6 are two small soluble electron carriers located in the intrathylacoidal space of cyanobacteria. although their role as electron shuttle between the cytochrome b6f and photosystem i complexes in the photosynthetic pathway is well established, their participation in the respiratory electron transport chain as donors to the terminal oxidase is still under debate. here, we present the first time-resolved analysis showing that both cytochrome c6 and plastocyanin can be ...	2005	15963511
carbohydrate, glycolipid, and lipid components from the photobiont (scytonema sp.) of the lichen, dictyomema glabratum.	the photobiont of the lichen, dictyonema glabratum (scytonema sp.), was isolated and cultivated in a soil-extract medium and submitted to chemical analysis. successive extractions with chcl3-meoh, aqueous meoh, and h2o gave rise to solutions of lipids (25%), low-molecular-weight carbohydrates (22%), and polysaccharides (4%), respectively. tlc of the lipid extract showed the presence of glycolipids, which were further purified and examined by nmr spectroscopy and gc-ms. monogalactosyldiacylglycer ...	2005	15963960
a papain-like enzyme at work: native and acyl-enzyme intermediate structures in phytochelatin synthesis.	phytochelatin synthase (pcs) is a key enzyme for heavy-metal detoxification in plants. pcs catalyzes the production of glutathione (gsh)-derived peptides (called phytochelatins or pcs) that bind heavy-metal ions before vacuolar sequestration. the enzyme can also hydrolyze gsh and gs-conjugated xenobiotics. in the cyanobacterium nostoc, the enzyme (nspcs) contains only the catalytic domain of the eukaryotic synthase and can act as a gsh hydrolase and weakly as a peptide ligase. the crystal struct ...	2005	16339904
transcription and autoregulation of the rv3134c-devr-devs operon of mycobacterium tuberculosis.	devr is a transcriptional regulator that mediates the genetic response of mycobacterium tuberculosis to oxygen limitation and nitric oxide exposure. devr is co-transcribed along with devs, which encodes its cognate sensor kinase, and an upstream gene, rv3134c. the transcriptional activity of this operon was characterized by primer extension, transcriptional fusion and electrophoretic mobility shift assays (emsas) under aerobic conditions. transcription start points (tsps) were detected upstream ...	2005	16339949
physiological and molecular diversity of feather moss associative n2-fixing cyanobacteria.	cyanobacteria colonizing the feather moss pleurozium schreberi were isolated from moss samples collected in northern sweden and subjected to physiological and molecular characterization. morphological studies of isolated and moss-associated cyanobacteria were carried out by light microscopy. molecular tools were used for cyanobacteria identification, and a reconstitution experiment of the association between non-associative mosses and cyanobacteria was conducted. the influence of temperature on ...	2005	16263908
crucial role of extracellular polysaccharides in desiccation and freezing tolerance in the terrestrial cyanobacterium nostoc commune.	the cyanobacterium nostoc commune is adapted to the terrestrial environment and has a cosmopolitan distribution. in this study, the role of extracellular polysaccharides (eps) in the desiccation tolerance of photosynthesis in n. commune was examined. although photosynthetic o2 evolution was not detected in desiccated colonies, the ability of the cells to evolve o2 rapidly recovered after rehydration. the air-dried colonies contained approximately 10% (wt/wt) water, and field-isolated, natural co ...	2005	16269775
characterization of nitrogen-fixing cyanobacteria in the brazilian amazon floodplain.	the diversity of the free-living nitrogen-fixing cyanobacterial community in the floodplain sediments along the solimões and amazon rivers and some of their tributaries (japurá, negro and madeira) was investigated. five cyanobacterial genera were morphologically identified, four of which (nostoc, calothrix, cylindrospermum and fischerella) have not previously been isolated from the brazilian amazon floodplain. nostoc strains were the most commonly found heterocyst-forming cyanobacteria. five str ...	2005	16289234
a study on the correlation of nucleotide skews and the positioning of the origin of replication: different modes of replication in bacterial species.	deviations from chargaff's 2nd parity rule, according to which a approximately t and g approximately c in single stranded dna, have been associated with replication as well as with transcription in prokaryotes. based on observations regarding mainly the transcription-replication co-linearity in a large number of prokaryotic species, we formulate the hypothesis that the replication procedure may follow different modes between genomes throughout which the skews clearly follow different patterns. w ...	2005	16321966
metabolites produced by nitrogen-fixing nostoc species.	this paper provides a comprehensive overview of metabolites, including lipids and lipid-like compounds, boron-containing macrocycles, arsenolipids, oligopeptides and amino acid derivatives, produced by cyanobacteria of the genus nostoc.	2005	16475497
crystallization and preliminary x-ray crystallographic analysis of the glur0 ligand-binding core from nostoc punctiforme.	glur0 from nostoc punctiforme (npglur0) is a bacterial homologue of the ionotropic glutamate receptor. the ligand-binding core of npglur0 was crystallized at 294 k using the hanging-drop vapour-diffusion method. the l-glutamate-complexed crystal belongs to space group c222(1), with unit-cell parameters a = 78.0, b = 145.1, c = 132.1 a. the crystals contain three subunits in the asymmetric unit, with a vm value of 2.49 a3 da(-1). the diffraction limit of the l-glutamate complex data set was 2.1 a ...	2005	16511224
poly-beta-hydroxybutyrate accumulation in nostoc muscorum and spirulina platensis under phosphate limitation.	nostoc muscorum and spirulina platensis were grown under phosphate deficiency in order to investigate the role of internal phosphate pool and activity of alkaline phosphatase on poly-beta-hydroxybutyrate (phb) accumulation. phb accumulation in n. muscorum increased to 22.7% of dry weight (dw) after 4 day of phosphate deficiency, while the internal phosphate pool reduced to the level of 0.02 microm mg dw(-1) at a maximum apase activity of 2.57nm pnp mg dw(-1) h(-1). in contrary, s. platensis depi ...	2005	16425456
nostocarboline: isolation and synthesis of a new cholinesterase inhibitor from nostoc 78-12a.	a new quaternary beta-carboline alkaloid, nostocarboline, was isolated from the freshwater cyanobacterium nostoc 78-12a, and its constitution was assigned by 2d-nmr methods. the structure was proven by its total synthesis starting from norharmane via chlorination at c-6 and methylation at n-2. nostocarboline was found to be a potent butyrylcholinesterase (bche) inhibitor, with an ic(50) of 13.2 microm. the related 2-methylnorharmane, which is present in the human brain and might be relevant to p ...	2005	16378379
biolingua: a programmable knowledge environment for biologists.	biolingua is an interactive, web-based programming environment that enables biologists to analyze biological systems by combining knowledge and data through direct end-user programming. biolingua embeds a mature symbolic programming language in a frame-based knowledge environment, integrating genomic and pathway knowledge about a class of similar organisms. the biolingua language provides interfaces to numerous state-of-the-art bioinformatic tools, making these available as an integrated package ...	2005	15308539
phylogeny of symbiotic cyanobacteria within the genus nostoc based on 16s rdna sequence analyses.	a phylogenetic analysis of selected symbiotic nostoc strain sequences and available database 16s rdna sequences of both symbiotic and free-living cyanobacteria was carried out using maximum likelihood and bayesian inference techniques. most of the symbiotic strains fell into well separated clades. one clade consisted of a mixture of symbiotic and free-living isolates. this clade includes nostoc sp. strain pcc 73102, the reference strain proposed for nostoc punctiforme. a separate symbiotic clade ...	2005	15549268