| anabaena flos-aquae and other cyanobacteria possess diadenosine 5',5"'-p1,p4-tetraphosphate (ap4a) phosphorylase activity. | diadenosine 5',5"'-p1,p4-tetraphosphate (ap4a) phosphorylase, previously only known in lower eukaryotes, has been detected in extracts of the cyanobacteria anabaena flos-aquae, anabaena variabilis and synechococcus sp. the 32 kda enzyme was partially purified from a. flos-aquae and separated from a 23 kda hydrolytic activity. it had a ph optimum of 9.5 and required a bivalent cation for activity: mg2+, mn2+, ca2+, co2+ or zn2+. diadenosine tri-, tetra- and penta-phosphates were all effective sub ... | 1996 | 9003364 |
| oxidative inactivation of glutamine synthetase from the cyanobacterium anabaena variabilis. | in crude extracts of the cyanobacterium anabaena variabilis, glutamine synthetase (gs) could be effectively inactivated by the addition of nadh. gs inactivation was completed within 30 min. both the inactivated gs and the active enzyme were isolated. no difference between the two enzyme forms was seen in sodium dodecyl sulfate-gels, and only minor differences were detectable by uv spectra, which excludes modification by a nucleotide. mass spectrometry revealed that the molecular masses of active ... | 1997 | 9006027 |
| identification and characterization of a gene encoding a vertebrate-type carbonic anhydrase in cyanobacteria. | a gene (designated ecaa) encoding a vertebrate-like (alpha-type) carbonic anhydrase (ca) has been isolated from two disparate cyanobacteria, anabaena sp. strain pcc 7120 and synechococcus sp. strain pcc 7942. the deduced amino acid sequences correspond to proteins of 29 and 26 kda, respectively, and revealed significant sequence similarity to human cai and caii, as well as chlamydomonas cahi, including conservation of most active-site residues identified in the animal enzymes. structural similar ... | 1997 | 9006032 |
| amino acid transport in taxonomically diverse cyanobacteria and identification of two genes encoding elements of a neutral amino acid permease putatively involved in recapture of leaked hydrophobic amino acids. | the activities of uptake of thirteen 14c-labeled amino acids were determined in nine cyanobacteria, including the unicellular strains synechococcus sp. strain pcc 7942 and synechocystis sp. strain pcc 6803; the filamentous strain pseudanabaena sp. strain pcc 6903, and the filamentous, heterocyst-forming strains anabaena sp. strains pcc 7120 and pcc 7937; nostoc sp. strains pcc 7413 and pcc 7107; calothrix sp. strain pcc 7601 (which is a mutant unable to develop heterocysts); and fischerella musc ... | 1997 | 9006043 |
| residue glu-91 of chlamydomonas reinhardtii ferredoxin is essential for electron transfer to ferredoxin-thioredoxin reductase. | the [2fe-2s] soluble ferredoxin from chlamydomonas reinhardtii was mutated by site directed mutagenesis, using pcr and the expression plasmid pet-fd as a template. the recombinant mutated proteins were purified to homogeneity and tested in the activation of nadp-malate dehydrogenase, a light dependent reaction in which ferredoxin thioredoxin reductase (ftr) and thioredoxin are involved. the mutation of residue glu-91 (e92 in spinach, e94 in anabaena) alone, either to gln (e91q) or to lys (e91k), ... | 1997 | 9009217 |
| joining the two domains of a group i ribozyme to form the catalytic core. | self-splicing group i introns, like other large catalytic rnas, contain structural domains. although the crystal structure of one of these domains has been determined by x-ray analysis, its connection to the other major domain that contains the guanosine-binding site has not been known. site-directed mutagenesis and kinetic analysis of rna splicing were used to identify a base triple in the conserved core of both a cyanobacterial (anabaena) and a eukaryotic (tetrahymena) group i intron. this lon ... | 1997 | 9012355 |
| a role for cpeyz in cyanobacterial phycoerythrin biosynthesis. | pigment mutant strain fdr1 of the filamentous cyanobacterium fremyella diplosiphon is characterized by constitutive synthesis of the phycobiliprotein phycoerythrin due to insertional inactivation of the rcac regulatory gene by endogenous transposon tn5469. whereas the parental strain fd33 harbors five genomic copies of tn5469, cells of strain fdr1 harbor six genomic copies of the element; the sixth copy in fdr1 is localized to the rcac gene. electroporation of fdr1 cells yielded secondary pigmen ... | 1997 | 9023176 |
| nmr solution structure of an oxidised thioredoxin h from the eukaryotic green alga chlamydomonas reinhardtii. | nmr solution structures of a cytosolic plant thioredoxin h (112 amino acids, 11.7 kda) from the green alga chlamydonmonas reinhardtii have been calculated on the basis of 1904 nmr distance restraints, which include 90 distances used to restrain 45 hydrogen bonds, and 44 phi dihedral restraints. the structure of c. reinhardtii thioredoxin h was solved in its oxidised form, and the ensemble of 23 converged structures superpose to the geometric average structure with an atomic rmsd of 0.080 nm +/- ... | 1997 | 9030762 |
| pyruvate: ferredoxin oxidoreductase from entamoeba histolytica recognized by a monoclonal antibody. | a mouse monoclonal antibody, eh208c2-2 mab, raised against whole cell antigens of entamoeba histolytica trophozoites of the pathogenic strain hm-1: imss and polyclonal antisera (pab) against membrane antigens of e. histolytica trophozoites of strain hth-56: mutm were screened against a cdna library of the pathogenic strain, sfl3. the monoconal antibody detected many phage plaques expressing an e. histolytica protein. the dna sequence encoding the protein was approximately 55% identical, over 1,1 ... | 1996 | 9031403 |
| disruption analysis of the gene for a cold-regulated rna-binding protein, rbpa1, in anabaena: cold-induced initiation of the heterocyst differentiation pathway. | a cold-regulated operon, rbpa1-rpsu, encodes an rna-binding protein and a ribosomal protein in anabaena variabilis m3. the level of expression of this gene cluster was about ten times higher at temperatures below 30 degrees c than at 38 degrees c. to study the role of the rbpa1 protein in vivo, we constructed insertional disruptants of rbpa1. these strains were totally devoid of rbpa1 protein but contained a normal level of the ribosomal protein s21, a product of the rpsu gene. the disruptants w ... | 1996 | 9032967 |
| differential regulation by low temperature of the gene for an rna-binding protein, rbpa3, in the cyanobacterium anabaena variabilis strain m3. | the rbpa3 protein of anabaena variabilis contains one rna-binding domain with a carboxy-terminal glycinerich domain. levels of two transcripts of the rbpa3 gene were differentially regulated by growth temperature. the rbpa3 protein is related to the rbpc protein within the group of cyanobacterial rbps. | 1997 | 9057337 |
| genes encoding proteins homologous to halobacterial gvps n, j, k, f & l are located downstream of gvpc in the cyanobacterium anabaena flos-aquae. | only two gas vesicle genes have been previously identified in the cyanobacteria, gvpa and gvpc, both of which encode structural gas vesicle proteins. analysis of the nucleotide sequence immediately downstream of gvpc in the cyanobacterium anabaena flos-aquae has revealed the presence of 4 orfs (open reading frames) the products of which share significant homology with a number of the gene products derived from halobacterial gvp gene clusters. in halobacteria the gas vesicle gene clusters consist ... | 1997 | 9063646 |
| reduction of conjugal transfer efficiency by three restriction activities of anabaena sp. strain pcc 7120. | the efficiency of conjugal transfer of plasmids from escherichia coli to the cyanobacterium anabaena sp. strain pcc 7120 was quantitated as a function of the number of restriction sites for the restriction enzymes carried by the recipient. in addition to the previously recognized isoschizomers of avai and avaii, pcc 7120 was found to possess an isoschizomer of avaiii. plasmids modified in e. coli with methylases that protect in vitro against restriction by the three enzymes were transferred with ... | 1997 | 9068647 |
| the heterocyst-specific fdxh gene product of the cyanobacterium anabaena sp. pcc 7120 is important but not essential for nitrogen fixation. | to clarify the role of the heterocyst-specific [2fe-2s] ferredoxin in cyanobacterial nitrogen fixation, mutational analysis of the anabaena 7120 fdxh gene region was carried out. first, the dna sequence of the wild-type 3509-bp ecori fragment downstream of the fdxh gene was determined. genes homologous to orf3 from the fdxh gene regions of a. variabilis and plectonema boryanum, the mop genes of clostridium pasteurianum encoding molybdo-pterin binding proteins, and orf3 from the a. variabilis hyd ... | 1997 | 9079890 |
| protein tyrosine phosphorylation in the cyanobacterium anabaena sp. strain pcc 7120. | components of a protein tyrosine phosphorylation/dephosphorylation network were identified in the cyanobacterium anabaena sp. strain pcc 7120. three phosphotyrosine (p-tyr) proteins of 27, 36, and 52 kda were identified through their conspicuous immunoreactions with rc20h monoclonal antibodies specific for p-tyr. these immunoreactions were outcompeted completely by free p-tyr (5 mm) but not by phosphoserine or phosphothreonine. the p-tyr content of the three major p-tyr proteins and several mino ... | 1997 | 9079918 |
| cell-type specificity of the anabaena fdxn-element rearrangement requires xish and xisi. | the fdxn element, along with two other dna elements, is excised from the chromosome during heterocyst differentiation in anabaena sp. strain pcc 7120. previous work showed that rearrangement of the fdxn element requires the xisf gene, which encodes a site-specific recombinase, and suggested that at least one other heterocyst-specific factor is involved. here we report that the xish and xisi genes are necessary for the heterocyst-specific excision of the fdxn element. deletion of a 3.2 kb region ... | 1997 | 9106215 |
| microcystins in slovene freshwaters (central europe)--first report. | cyanobacterial blooms are frequent in the north-eastern region of slovenia, where the agricultural activities are intensive, resulting in higher water eutrophication. in a two year monitoring program we identified eighteen blooms of cyanobacteria, fifteen being hepatotoxic by intraperitoneal mouse bioassay. the approximate ld100 varied from 50-1000 mg/kg (dry cell weight/animal weight) and gross pathological signs were characteristic of cyanobacterial hepatotoxins. frequently the blooms were dom ... | 1997 | 9131592 |
| lipopolysaccharide dependence of cyanophage sensitivity and aerobic nitrogen fixation in anabaena sp. strain pcc 7120. | fox- mutants of anabaena sp. strain pcc 7120 are unable to fix dinitrogen in the presence of oxygen. a fragment of the dna of anabaena sp. was cloned by complementation of a spontaneous fox-, cyanophage-resistant mutant, r56, and characterized. random insertion of transposon tn5 delimited the complementing dna to a 0.6-kb portion of the cloned fragment. sequencing of this region and flanking dna showed one complete open reading frame (orf) similar to the gene rfbp (undecaprenyl-phosphate galacto ... | 1997 | 9139904 |
| identification and characterization of the nifv-nifz-nift gene region from the filamentous cyanobacterium anabaena sp. strain pcc 7120. | the nifv and leua genes, which encode homocitrate synthase and alpha-isopropylmalate synthase, respectively, were cloned from the filamentous cyanobacterium anabaena sp. strain pcc 7120 by a pcr-based strategy. since the n-terminal parts of nifv and leua from other bacteria are highly similar to each other, a single pair of pcr primers was used to amplify internal fragments of both anabaena strain 7120 genes. sequence analysis of cloned pcr products confirmed the presence of two different nifv-l ... | 1997 | 9139910 |
| dechlorination of lindane by the cyanobacterium anabaena sp. strain pcc7120 depends on the function of the nir operon. | nitrate is essential for lindane dechlorination by the cyanobacteria anabaena sp. strain pcc7120 and nostoc ellipsosporum, as it is for dechlorination of other organic compounds by heterotrophic microorganisms. based on analyses of mutants and effects of environmental factors, we conclude that lindane dechlorination by anabaena sp. requires a functional nir operon that encodes the enzymes for nitrate utilization. | 1997 | 9150239 |
| plasmodium falciparum glucose-6-phosphate dehydrogenase (g6pd)-the n-terminal portion is homologous to a predicted protein encoded near to g6pd in haemophilus influenzae. | | 1997 | 9157254 |
| a new cellulase family. | | 1997 | 9157255 |
| the nuia gene from anabaena sp. encoding an inhibitor of the nuca sugar-non-specific nuclease. | many filamentous, heterocyst-forming cyanobacteria express a sugar-non-specific nuclease of about 29 kda that can be detected in dna-containing sds-page gels. the nuca gene encoding this nuclease has previously been cloned from anabaena sp. pcc 7120, sequenced and expressed in escherichia coli. the nuca protein bears a putative signal peptide close to its n-terminal end and, in anabaena cultures, is present in both the cells and the extracellular medium. cell-free extracts of different cyanobact ... | 1997 | 9171282 |
| isolation and characterization of multiple adenylate cyclase genes from the cyanobacterium anabaena sp. strain pcc 7120. | adenylate cyclase genes, designated cyaa, cyab1, cyab2, cyac, and cyad, were isolated from the filamentous cyanobacterium anabaena sp. strain pcc 7120 by complementation of a strain of escherichia coli defective for the presence of cya. these genes encoded polypeptides consisting of 735, 859, 860, 1,155, and 546 amino acid residues, respectively. deduced amino acid sequences of the regions near the c-terminal ends of these cya genes were similar to those of catalytic domains of eukaryotic adenyl ... | 1997 | 9171404 |
| evidence for the bacterial origin of genes encoding fermentation enzymes of the amitochondriate protozoan parasite entamoeba histolytica. | entamoeba histolytica is an amitochondriate protozoan parasite with numerous bacterium-like fermentation enzymes including the pyruvate:ferredoxin oxidoreductase (por), ferredoxin (fd), and alcohol dehydrogenase e (adhe). the goal of this study was to determine whether the genes encoding these cytosolic e. histolytica fermentation enzymes might derive from a bacterium by horizontal transfer, as has previously been suggested for e. histolytica genes encoding heat shock protein 60, nicotinamide nu ... | 1997 | 9171424 |
| maximum activity of recombinant ribulose 1,5-bisphosphate carboxylase/oxygenase of anabaena sp. strain ca requires the product of the rbcx gene. | filamentous cyanobacteria of the genus anabaena contain a unique open reading frame, rbcx, which is juxtaposed and cotranscribed with the genes (rbcl and rbcs) encoding form i ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco). plasmid constructions containing the genes from anabaena sp. strain ca were prepared, and expression studies in escherichia coli indicated that the product of the rbcx gene mimicked the ability of chaperonin proteins to facilitate the proper folding of recombinant ... | 1997 | 9171433 |
| variation of microcystins, cyanobacterial hepatotoxins, in anabaena spp. as a function of growth stimuli. | cyanobacterial hepatotoxins, microcystins, are specific inhibitors of serine/threonine protein phosphatases and potent tumor promoters. they have caused several poisonings of animals and also pose a health hazard for humans through the use of water for drinking and recreation. different strains of the same cyanobacterial species may variously be nontoxic, be neurotoxic, or produce several microcystin variants. it is poorly understood how the amount of toxins varies in a single strain. this labor ... | 1997 | 9172340 |
| direct observation of protein secondary structure in gas vesicles by atomic force microscopy. | the protein that forms the gas vesicle in the cyanobacterium anabaena flos-aquae has been imaged by atomic force microscopy (afm) under liquid at room temperature. the protein constitutes "ribs" which, stacked together, form the hollow cylindrical tube and conical end caps of the gas vesicle. by operating the microscope in deflection mode, it has been possible to achieve sub-nanometer resolution of the rib structure. the lateral spacing of the ribs was found to be 4.6 +/- 0.1 nm. at higher resol ... | 1996 | 9172769 |
| compositional biases of bacterial genomes and evolutionary implications. | we compare and contrast genome-wide compositional biases and distributions of short oligonucleotides across 15 diverse prokaryotes that have substantial genomic sequence collections. these include seven complete genomes (escherichia coli, haemophilus influenzae, mycoplasma genitalium, mycoplasma pneumoniae, synechocystis sp. strain pcc6803, methanococcus jannaschii, and pyrobaculum aerophilum). a key observation concerns the constancy of the dinucleotide relative abundance profiles over multiple ... | 1997 | 9190805 |
| suppression of heterocyst differentiation in anabaena pcc 7120 by a cosmid carrying wild-type genes encoding enzymes for fatty acid synthesis. | a cosmid containing a wild-type anabaena pcc 7120 dna fragment was found to suppress heterocyst differentiation, creating a het phenotype in an otherwise wild-type strain. curing of the cosmid restored the full wild-type het+ nif+ phenotype. the cosmid contains at least four genes encoding proteins with significant sequence similarity to enzymes involved in the synthesis of fatty acids. selection for nif+ revertants of the suppressed strain yielded modified cosmids, one of which contained a 10.2 ... | 1997 | 9198279 |
| strain characterization and classification of oxyphotobacteria in clone cultures on the basis of 16s rrna sequences from the variable regions v6, v7, and v8. | a major problem in development of a polyphasic taxonomy is that the identification of oxyphotobacterial strains (cyanobacteria and prochlorophytes) in culture collections may be incorrect. we have therefore developed a diagnostic system using the dna sequence polymorphism in the 16s rrna regions v6 to v8 for individual strain characterization and identification. pcr primers amplifying v6 to v8 from oxyphotobacteria in unialgal cultures were constructed. direct solid-phase or cyclic sequencing wa ... | 1997 | 9212409 |
| detection of an anatoxin-a(s)-like anticholinesterase in natural blooms and cultures of cyanobacteria/blue-green algae from danish lakes and in the stomach contents of poisoned birds. | ten natural bloom samples of cyanobacteria from the danish lakes knud sø (5), ravn sø (4), and salten langsø (1) collected during 1993-1995 were assayed for toxicity by mouse bioassay, for acetylcholinesterase inhibiting activity by a colorimetric method, and for microcystins by enzyme-linked immunosorbent assay. in the mouse bioassay, seven samples were neurotoxic, two were non-toxic and one gave a protracted toxic response. one of the non-toxic and the single protracted toxic sample both conta ... | 1997 | 9241784 |
| anatoxin-a in irish freshwater and cyanobacteria, determined using a new fluorimetric liquid chromatographic method. | a new sensitive high-performance liquid chromatographic (hplc) method was used to determine anatoxin-a in freshwater, following blooms of cyanobacteria (blue-green algae). anatoxin-a was converted into a highly fluorescent derivative using 4-fluoro-7-nitro-2,1,3-benzoxadiazole and hplc analysis gave good linear calibrations even at low concentration ranges (1-10 micrograms/liter, r = 0.997). the detection limit for anatoxin-a was 0.02 ng/ml, and this new hplc method should prove useful for the r ... | 1997 | 9241789 |
| probing the influence of mutations on the stability of a ferredoxin by mass spectrometry. | hydrogen/deuterium exchange, which depends on solvent accessibility, can be probed by mass spectrometry (ms) to get information on protein conformation or protein-ligand interaction. in this work, the conformational properties of the cyanobacterium anabaena wild-type ferredoxin as well as of two single-site mutants (phe 65 ala and arg 42 ala) were studied. after incubation of the wild type and mutant proteins in deuterated water and quenching of the exchange at low ph, the proteins were rapidly ... | 1997 | 9246639 |
| characterization of genes for a second mo-dependent nitrogenase in the cyanobacterium anabaena variabilis. | anabaena variabilis atcc 29413 is a filamentous heterocystous cyanobacterium that fixes nitrogen under a variety of environmental conditions. under aerobic growth conditions, nitrogen fixation depends upon differentiation of heterocysts and expression of either a mo-dependent nitrogenase or a v-dependent nitrogenase in those specialized cells. under anaerobic conditions, a second mo-dependent nitrogenase gene cluster, nifii, was expressed in vegetative cells long before heterocysts formed. a str ... | 1997 | 9260968 |
| negatively charged anabaena flavodoxin residues (asp144 and glu145) are important for reconstitution of cytochrome p450 17alpha-hydroxylase activity. | catalysis by microsomal cytochromes p450 requires the membrane-bound enzyme nadph-cytochrome p450 reductase (p450 reductase), which transfers electrons to the p450 heme via a flavodoxin-like domain. previously, we reported that escherichia coli flavodoxin (fld), a soluble electron transfer protein, directly interacts with bovine cytochrome p450 17alpha-hydroxylase/17,20-lyase (p450c17) and donates electrons to this enzyme when reconstituted with nadph-ferredoxin (flavodoxin) reductase (fnr) (jen ... | 1997 | 9278403 |
| seasonal variations in microcystin contents of danish cyanobacteria. | one hundred ninety-eight of 296 phytoplankton net samples, collected from danish fresh waters during 1993-1995, contained microcystins when analyzed by high-performance liquid chromatography (hplc), and the seasonal variations in microcystin contents were examined. three genera, anabaena, microcystis, and planktothrix, with microcystin-production potential were found. the highest percentage of the samples dominated by anabaena and microcystis was found in june-july and july-november, respectivel ... | 1997 | 9285913 |
| structure-function relationships in anabaena ferredoxin: correlations between x-ray crystal structures, reduction potentials, and rate constants of electron transfer to ferredoxin:nadp+ reductase for site-specific ferredoxin mutants. | a combination of structural, thermodynamic, and transient kinetic data on wild-type and mutant anabaena vegetative cell ferredoxins has been used to investigate the nature of the protein-protein interactions leading to electron transfer from reduced ferredoxin to oxidized ferredoxin:nadp+ reductase (fnr). we have determined the reduction potentials of wild-type vegetative ferredoxin, heterocyst ferredoxin, and 12 site-specific mutants at seven surface residues of vegetative ferredoxin, as well a ... | 1997 | 9287153 |
| mutagenesis and comparative sequence analysis of a base triple joining the two domains of group i ribozymes. | tertiary interactions are important in the higher-order folding of catalytic rnas. recently, a base triple, joining the two major domains of the catalytic core, was determined in group i introns from the cyanobacterium anabaena pcc7120 and the eukaryote tetrahymena thermophila. this base triple involves the fifth base pair of p4 and the fifth base of the single-stranded region j8/7. we made base pair and single-nucleotide substitutions in the fifth base pair of p4, a g-c in the wild-type anabaen ... | 1997 | 9292502 |
| rapid typing and elucidation of new secondary metabolites of intact cyanobacteria using maldi-tof mass spectrometry. | toxic cyanobacterial blooms are a threat because of secondary metabolite production. we used matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to identify intact microorganisms. microgram quantities of prepared cells, including solvent (acetonitrile and ethanol) and alpha-cyano-4-hydroxycinnamic acid matrix, display spectra showing predominantly the secondary metabolites including known microcystins, micropeptin, and anabaenopeptolin. a new cyclic anabaenopeptolin has ... | 1997 | 9306409 |
| a multitype branching process model for blue-green algae. | in this article, a multitype branching process is proposed for the behavior of populations of linear clusters of cells. the main results concern the asymptotic cluster size distribution. | 1997 | 9309931 |
| nitrate assimilation by bacteria. | nitrate is a significant nitrogen source for plants and microorganisms. recent molecular genetic analyses of representative bacterial species have revealed structural and regulatory genes responsible for the nitrate-assimilation phenotype. together with results from physiological and biochemical studies, this information has unveiled fundamental aspects of bacterial nitrate assimilation and provides the foundation for further investigations. well-studied genera are: the cyanobacteria, including ... | 1998 | 9328645 |
| arginine294 is essential for the inhibition of anabaena pcc 7120 adp-glucose pyrophosphorylase by phosphate. | treatment of adp-glucose pyrophosphorylase (ec 2.7.7.27) from the cyanobacterium anabaena pcc 7120 with phenylglyoxal in 50 mm hepes, ph 8.0, at 25 degrees c resulted in a time- and concentration-dependent loss of enzyme activity. phosphate, the inhibitor, protected the enzyme from inactivation most effectively, while 3-p-glycerate, fructose-1,6-p2, pyridoxal-p, and atp plus magnesium were also good protectors. after incubation with 2 mm phenylglyoxal for 1 h, the modified enzyme had a 10-fold l ... | 1997 | 9335570 |
| nitrobenzimidazoles as substrates for dt-diaphorase and redox cycling compounds: their enzymatic reactions and cytotoxicity. | we have synthesized a number of nitrobenzimidazoles containing nitro groups in the benzene ring and found that they acted as relatively efficient substrates for rat liver dt-diaphorase (ec 1.6.99.2), their reactivity exceeding reactivities of nitrofurans and nitrobenzenes. nitrobenzimidazoles were competitive with nadph inhibitors of dt-diaphorase in menadione reductase reactions, their inhibition constant being unchanged in the presence of dicumarol and being increased in the presence of 2',5'- ... | 1997 | 9343369 |
| programmed cell death in prokaryotes. | programmed cell death (pcd), also referred to as apoptosis, is a cellular "suicide" mechanism, based on information from its own internal metabolism, environment, developmental history, and genome. this system was described in eukaryotes continuously along evolution, through amoebae, nematodes, insects, and animals. pcd is essential for the proper development or function of a cell system, organ, or survival of the organism as a whole. research in the last 2 decades has shown that the life cycle ... | 1997 | 9347220 |
| evidence for redox regulation of the transcription factor ntca, acting both as an activator and a repressor, in the cyanobacterium anabaena pcc 7120. | ntca has been identified as a nitrogen-responsive regulatory protein required for nitrogen assimilation and heterocyst differentiation in cyanobacteria. it is proposed that ntca functions through the formation of dna-protein complexes with its specific target sequence within the promoter regions of the regulated genes. in vitro, ntca of anabaena pcc 7120 binds to upstream regions of the genes whose products are involved in nitrogen assimilation, but also to the upstream region of rbcls (carbon-f ... | 1997 | 9359424 |
| thioredoxin from bacillus acidocaldarius: characterization, high-level expression in escherichia coli and molecular modelling. | the thioredoxin (trx) from bacillus acidocaldarius (bactrx) was purified to homogeneity by anion-exchange chromatography and gel-filtration chromatography, based on its ability to catalyse the dithiothreitol-dependent reduction of bovine insulin disulphides. the protein has a molecular mass of 11577 da, determined by electrospray mass spectrometry, a pi of 4.2, and its primary structure was obtained by automated edman degradation after cleavage with trypsin and cyanogen bromide. the sequences of ... | 1997 | 9359865 |
| hetc, a gene coding for a protein similar to bacterial abc protein exporters, is involved in early regulation of heterocyst differentiation in anabaena sp. strain pcc 7120. | transposon-generated mutant c3 of anabaena sp. strain pcc 7120 is unable to form heterocysts upon deprivation of combined nitrogen but forms a pattern of spaced, weakly fluorescent cells after 2 days of deprivation. sequence analysis of chromosomal dna adjacent to the ends of transposon tn5-1058 in mutant c3 showed a 1,044-amino-acid open reading frame, designated hetc, whose predicted protein product throughout its c-terminal two-thirds has extensive similarity to the hlyb family of bacterial p ... | 1997 | 9371442 |
| temperature-dependent regulation of the ribosomal small-subunit protein s21 in the cyanobacterium anabaena variabilis m3. | the rpsu gene, which encodes the ribosomal small-subunit protein s21 in anabaena, is not a part of the macromolecular-synthesis operon as in most enterobacteria but rather is located downstream of the rbpa1 gene, which encodes an rna-binding protein. two types of transcripts were detected for this gene cluster. the level of the major rbpa1-rpsu transcript was about 10 times higher at 22 degrees c than at 38 degrees c, whereas the minor monocistronic rpsu transcript was more abundant at the highe ... | 1997 | 9371454 |
| effect of light irradiance on the production of sulfolipids from anabaena 7120 in a fed-batch photobioreactor. | sulfolipids have recently emerged as promising antihiv and antitumor therapeutics. these lipids have been found in association with the photosynthetic apparatus in most photoautotrophic organisms. to date there have been no quantitative studies on the effect of environmental factors on the production of sulfolipid. in this study, we present results on the effect of light irradiance on the production of sulfolipids using the cyanobacterium anabaena 7120. the cyanobacteria are grown in a 2 l fed-b ... | 1997 | 9382487 |
| characterization of cyanobacteria by sds-page of whole-cell proteins and pcr/rflp of the 16s rrna gene. | planktonic, filamentous cyanobacterial strains from different genera, both toxic and nontoxic strains, were characterized by sds-page of whole-cell proteins and pcr/rflp of the 16s rrna gene. total protein pattern analysis revealed the mutual relationships at the genus level. restriction fragment length polymorphism (rflp) of the 16s rrna gene with reference strains proved to be a good method for the cyanobacterial taxonomy. the nonheterocystous strains outgrouped from the nitrogen-fixing ones. ... | 1997 | 9382701 |
| differential stabilization of the three fmn redox forms by tyrosine 94 and tryptophan 57 in flavodoxin from anabaena and its influence on the redox potentials. | flavodoxins are electron transfer proteins that carry a noncovalently bound flavin mononucleotide molecule as the redox-active center. the redox potentials of the flavin nucleotide are profoundly altered upon interaction with the protein. in anabaena flavodoxin, as in many flavodoxins, the flavin is sandwiched between two aromatic residues (trp57 and tyr94) thought to be implicated in the alteration of the redox potentials. we have individually replaced these two residues by each of the other ar ... | 1997 | 9398151 |
| iron-sulfur cluster cysteine-to-serine mutants of anabaena -2fe-2s- ferredoxin exhibit unexpected redox properties and are competent in electron transfer to ferredoxin:nadp+ reductase. | the reduction potentials and the rate constants for electron transfer (et) to ferredoxin:nadp+ reductase (fnr) are reported for site-directed mutants of the [2fe-2s] vegetative cell ferredoxin (fd) from anabaena pcc 7120, each of which has a cluster ligating cysteine residue mutated to serine (c41s, c46s, and c49s). the x-ray crystal structure of the c49s mutant has also been determined. the uv-visible optical and cd spectra of the mutants differ from each other and from wild-type (wt) fd. this ... | 1997 | 9398238 |
| one- and two-dimensional eseem spectroscopy of flavoproteins. | one- and two-dimensional (1d and 2d) electron spin echo envelope modulation (eseem) spectroscopy was applied to study the flavin cofactors in the neutral semiquinone states of flavodoxin and ferredoxin-nadp+ reductase (fnr) from the cyanobacterium anabaena pcc 7119, and the anionic semiquinone state of cholesterol oxidase from brevibacterium sterolicum. high-resolution crystal structures are available for all these proteins. three- and 4-pulse eseem and hyperfine sublevel correlation spectroscop ... | 1997 | 9398281 |
| mosquito larvicidal activity of transgenic anabaena strain pcc 7120 expressing combinations of genes from bacillus thuringiensis subsp. israelensis. | various combinations of the genes cryiva (cry4a), cryivd (cry11a), and p20 from bacillus thuringiensis subsp. israelensis were introduced into the nitrogen-fixing cyanobacterium anabaena sp. strain pcc 7120 by means of escherichia coli-anabaena shuttle vector prl488p and were expressed under control of two tandem strong promoters, a cyanobacterial promoter (ppsba) and an e. coli t7 promoter (pa1). two of the clones carrying cryiva plus cryivd, one with p20 and one without p20, displayed toxicity ... | 1997 | 9406420 |
| effects of the herbicide molinate on mixotrophic growth, photosynthetic pigments, and protein content of anabaena sphaerica under different light conditions. | the effects of the carbamate herbicide molinate on growth and chlorophyll a, biliprotein, and protein content of the nitrogen-fixing cyanobacterium anabaena sphaerica grown mixotrophically under 3000- and 300-lux light intensity were studied. under two light intensities, the three concentrations of molinate tested (5, 25, and 50 microg ml-1) can significantly inhibit algal growth in a dose-dependent manner. the high concentration of molinate (50 microg ml-1) stimulated the synthesis of chlorophy ... | 1997 | 9417856 |
| the rhodobacter capsulatus hupslc promoter: identification of cis-regulatory elements and of trans-activating factors involved in h2 activation of hupslc transcription. | the [nife]hydrogenase of the photosynthetic bacterium rhodobacter capsulatus is encoded by the structural hupslc operon, the expression of which is induced by h2. h2 activation was no longer observable in chromosomal hupr mutants, an indication that hupr is implicated directly in the activation by h2 of hups gene expression. the transcriptional start site of the hups promoter, determined by primer extension mapping, was located 55 nucleotides upstream from the translational start codon of the hu ... | 1997 | 9426130 |
| confirmation of anatoxin-a(s), in the cyanobacterium anabaena lemmermannii, as the cause of bird kills in danish lakes. | cyanobacterial blooms were implicated in bird kills at lakes in denmark in july 1993 and june-july 1994. these blooms were dominated by anabaena lemmermannii and were shown to contain a neurotoxin with anticholinesterase activity. in this study, the toxin was isolated by mouse lethality guided column chromatographies from the field sample collected at lake knud sø in 1993. various spectroscopic data indicated that the toxin was anatoxin-a(s), an irreversible anticholinesterase, first reported in ... | 1997 | 9428111 |
| expression of the mouse metallothionein-i gene conferring cadmium resistance in a transgenic cyanobacterium. | this paper reports the construction of a transgenic strain of cyanobacterium aimed at removing heavy metal pollution in waters. the mouse metallothionein-i (mmt-i) gene was inserted in the vector prl-439 downstream of the strong psba promoter. the resulting plasmid prl-mt was ligated at the ecori site of the shuttle vector pkt-210 to generate the shuttle expression vector pkt-mt. this recombinant plasmid was introduced into anabaena sp. pcc 7120 by triparental conjugative transfer. after selecti ... | 1998 | 9453164 |
| the 2.15 a crystal structure of a triple mutant plastocyanin from the cyanobacterium synechocystis sp. pcc 6803. | the crystal structure of the triple mutant a42d/d47p/a63l plastocyanin from the cyanobacterium synechocystis sp. pcc 6803 has been determined by patterson search methods using the known structure of the poplar protein. crystals of the triple mutant a42d/d47p/a63l, which are stable for days in its oxidized form, were grown from ammonium sulfate, with the cell constants a = b = 34.3 a and c = 111.8 a belonging to space group p3(2)21. the structure was refined using restrained crystallographic refi ... | 1998 | 9466912 |
| disappearance of linear alkylbenzene sulfonate from different cultures with anabaena sp. hb 1017. | | 1998 | 9470998 |
| cloning and correct expression in escherichia coli of the pete and petj genes respectively encoding plastocyanin and cytochrome c6 from the cyanobacterium anabaena sp. pcc 7119. | the genes coding for plastocyanin (pete) and cytochrome c6 (petj) from anabaena sp. pcc 7119 have been cloned and properly expressed in escherichia coli. the recombinant proteins are identical to those purified from the cyanobacterial cells. the products of both the pete and petj genes are correctly processed in e. coli, as deduced from their identical n-terminal amino acid sequences as compared with those of the metalloproteins isolated from the cyanobacterium. physicochemical and functional pr ... | 1998 | 9473522 |
| involvement of glutamic acid 301 in the catalytic mechanism of ferredoxin-nadp+ reductase from anabaena pcc 7119. | the crystal structure of anabaena pcc 7119 ferredoxin-nadp+ reductase (fnr) suggests that the carboxylate group of glu301 may be directly involved in the catalytic process of electron and proton transfer between the isoalloxazine moiety of fad and fnr substrates (nadph, ferredoxin, and flavodoxin). to assess this possibility, the carboxylate of glu301 was removed by mutating the residue to an alanine. various spectroscopic techniques (uv-vis absorption, fluorescence, and cd) indicate that the mu ... | 1998 | 9485422 |
| biochemical characterization of anabaena sp. strain pcc 7120 non-specific nuclease nuca and its inhibitor nuia. | we have established overexpression systems and purification protocols for nuca and nuia, a sugar non-specific nuclease and its protein inhibitor from anabaena sp. strain pcc 7120, in order to characterize these proteins in detail. cd spectroscopy revealed that nuca has a similar secondary-structure composition, 13% alpha helix and 20% beta sheet, to the related serratia nuclease, while nuia represents a protein with a higher alpha-helical (29%) and beta-sheet (24%) content than nuca. denaturatio ... | 1998 | 9490069 |
| rhodobacter capsulatus hypf is involved in regulation of hydrogenase synthesis through the hupuv proteins. | the photosynthetic bacterium rhodobacter capsulatus contains a membrane-bound [nife]hydrogenase encoded by the hupsl genes. we show in this study that hypf mutants are devoid of hydrogenase activity and lack the hupl protein. we also observed that, in contrast to the wild-type strain b10, transcription of the hupsl genes was not stimulated by h2 in the hypf mutants rs13 and bse19. complementation of the hypf mutants with the plasmid borne hypf gene restored hydrogenase activity to wild-type leve ... | 1998 | 9492269 |
| the role of aromatic and acidic amino acids in the electron transfer reaction catalyzed by spinach ferredoxin-dependent glutamate synthase. | treatment of the ferredoxin-dependent, spinach glutamate synthase with n-bromosuccinimide (nbs) modifies 2 mol of tryptophan residues per mol of enzyme, without detectable modification of other amino acids, and inhibits enzyme activity by 85% with either reduced ferredoxin or reduced methyl viologen serving as the source of electrons. the inhibition of ferredoxin-dependent activity resulting from nbs treatment arises entirely from a decrease in the turnover number. complex formation of glutamate ... | 1998 | 9507092 |
| interaction of positively charged amino acid residues of recombinant, cyanobacterial ferredoxin:nadp+ reductase with ferredoxin probed by site directed mutagenesis. | the peth genes encoding ferredoxin:nadp+ reductase (fnr) from two anabaena species (pcc 7119 and atcc 29413) were cloned and overexpressed in e. coli. several positively charged residues (arg, lys) have been implicated to be involved in ferredoxin binding and electron transfer by cross-linking, chemical modification and protection experiments, and crystallographic studies. the following substitutions were introduced by site-directed mutagenesis: r153q, k209q, k212q, r214q, k275n, k430q and k431q ... | 1998 | 9511808 |
| seven new microcystins possessing two l-glutamic acid units, isolated from anabaena sp. strain 186. | electrospray ionization mass spectrometry has been applied to the structure assignment of seven new microcystins (1-7), obtained from cultured anabaena sp. strain 186. the seven new microcystins contain the dehydroalanine (dha) or l-ser unit instead of the n-methyldehydroalanine unit and the l-glu and/or its delta-methyl ester [e(ome)] units at the two variable l-amino acid units, and the structures were assigned as [dha7]microcystin-e(ome)e(ome) (1), [d-asp3,dha7]microcystin-e(ome)e(ome) (2), [ ... | 1998 | 9511906 |
| uvb-induced reduction in biomass and overall productivity of cyanobacteria. | effect of middle wave ultraviolet radiation (uvb) was studied in three different species of cyanobacteria (nostoc, anabaena and scytonema) by estimating their growth pattern, biomass yield, chlorophyll content, total starch and protein content. the results show that exposure of the cyanobacteria with uvb dose corresponding to an increase or decrease of 20% in its environmental flux will have drastic effects on biomass production, photosynthetic rate and nitrogen fixation. cyanobacteria are prima ... | 1998 | 9514891 |
| identification of 10sa rna (tmrna) homologues from the cyanobacterium synechococcus sp. strain pcc6301 and related organisms. | we have isolated the 10sa rna (tmrna) from the unicellular cyanobacterium synechococcus sp. strain pcc6301. it comprises of 394 nucleotides (nt) and has 55% homology to escherichia coli tmrna. the cloning and sequencing of the corresponding gene have revealed that, like in many trna genes, the terminal cca sequence reported in all the tmrna species characterized so far is not encoded in the dna. hybridization analysis has shown that the tmrna gene is present as a single copy. fairly high levels ... | 1998 | 9524235 |
| a higher-plant type zeta-carotene desaturase in the cyanobacterium synechocystis pcc6803. | the genomic dna sequence of synechocystis was analysed for putative zeta-carotene desaturase genes. two promising candidates slr0940 and slr0033 were found with similarities to the structurally different zeta-carotene desaturase genes from higher plants and anabaena, respectively. only the expression product of the analogue to the plant gene, slr0940, was able to mediate the 2-step desaturation of zeta-carotene via neurosporene to lycopene after complementation of this pathway in escherichia col ... | 1998 | 9526505 |
| hydrogen uptake in nostoc sp. strain pcc 73102. cloning and characterization of a hupsl homologue. | structural genes encoding an uptake hydrogenase of nostoc sp. strain pcc 73102 were isolated. from partial libraries of genomic dna, two clones (pnfo01 and pnfo02) were selected and sequenced, revealing the complete sequence of both a hups (960 bases) and a hupl (1,593 bases) homologue in nostoc sp. strain pcc 73102. a comparison between the deduced amino acid sequences of hups and hupl of nostoc sp. strain pcc 73102 and anabaena sp. strain pcc 7120 showed that the hups proteins are 89% identica ... | 1998 | 9531626 |
| unusual gene arrangement of the bidirectional hydrogenase and functional analysis of its diaphorase subunit hoxu in respiration of the unicellular cyanobacterium anacystis nidulans | the bidirectional, nad+-dependent hydrogenase from cyanobacteria is encoded by the structural genes hoxfuyh, which have been found to be clustered, though interspersed with different open reading frames (orfs), in the heterocystous, n2-fixing anabaena variabilis and in the unicellular synechocystis pcc 6803. in another unicellular, non n2-fixing cyanobacterium, anacystis nidulans, hoxf has now been identified as being separated by at least 16 kb from the residual structural genes hoxuyh. an orf ... | 1998 | 9541559 |
| involvement of the 5'-untranslated region in cold-regulated expression of the rbpa1 gene in the cyanobacterium anabaena variabilis m3. | transcript of the rbpa1 gene in anabaena variabilis accumulates significantly at low growth temperatures below 28 degreesc. this accumulation was maximal at 16 degreesc. accumulation of the rbpa1 transcript was completely abolished by rifampicin, but not by chloramphenicol. photosynthesis was not required for this cold-induced accumulation. this accumulation of transcript was partly accounted for by increased stability of the rbpa1 transcript at low temperature. expression of chimeric genes cont ... | 1998 | 9547280 |
| evidence that hetr protein is an unusual serine-type protease. | the hetr gene plays a very important role in cell differentiation of heterocystous cyanobacteria. to understand the mechanism of the hetr gene product in regulation of heterocyst differentiation, the recombinant hetr protein (rhetr) was overproduced in escherichia coli. purified rhetr was unstable and degraded easily in solution. phenylmethanesulfonyl fluoride, a serine-type protease inhibitor, prevented the degradation and was shown to modify covalently rhetr. dansyl fluoride (dnsf), another se ... | 1998 | 9560210 |
| characterization of hetr protein turnover in anabaena sp. pcc 7120. | the hetr gene plays an important role in heterocyst development and pattern formation in heterocystous cyanobacteria. the hetr gene from anabaena sp. pcc 7120 was overexpressed in escherichia coli. antibodies raised against the recombinant hetr protein (rhetr) were used to characterize metabolism of the hetr of anabaena sp. pcc 7120 in vivo. hetr was present at a low level when anabaena sp. pcc 7120 was grown in the presence of combined nitrogen. shifting from nitrogen repletion conditions to ni ... | 1998 | 9560423 |
| microbial production of hydrogen: an overview. | production of hydrogen by anaerobes, facultative anaerobes, aerobes, methylotrophs, and photosynthetic bacteria is possible. anaerobic clostridia are potential producers and immobilized c. butyricum produces 2 mol h2/mol glucose at 50% efficiency. spontaneous production of h2 from formate and glucose by immobilized escherichia coli showed 100% and 60% efficiencies, respectively. enterobactericiae produces h2 at similar efficiency from different monosaccharides during growth. among methylotrophs, ... | 1998 | 9561824 |
| genetic engineering, production and characterisation of monomeric variants of the dimeric serratia marcescens endonuclease. | the serratia nuclease is a non-specific endonuclease which cleaves single- and double-stranded rna and dna. it is a member of a large family of related endonucleases, most of which are dimers of identical subunits, with the notable exception of the anabaena nuclease which is a monomer. in order to find out whether the dimer state of the serratia nuclease is essential for its function we have produced variants of this nuclease which based on the crystal structure (miller, m.d. and krause, k.l. (1 ... | 1998 | 9563525 |
| the devbca exporter is essential for envelope formation in heterocysts of the cyanobacterium anabaena sp. strain pcc 7120. | the gene deva of the filamentous heterocyst-form-ing cyanobacterium anabaena sp. strain pcc 7120 encodes a protein with high similarity to atp-binding cassettes of abc transporters. mutant m7 defective in the deva gene is arrested in the development of heterocysts at an early stage and is not able to fix n2 under aerobic conditions. the deva gene is differentially expressed in heterocysts. to gain a better understanding of the structural components of this putative abc transporter, we determined ... | 1998 | 9570404 |
| reconstitution, characterisation and mass analysis of the pentacylindrical allophycocyanin core complex from the cyanobacterium anabaena sp. pcc 7120. | the phycobilisome (pbs) of anabaena sp. pcc 7120 was allowed to dissociate into its constituents and the resulting allophycocyanin (ap) fraction was purified. its reconstitution yielded a complex which according to negative stain electron microscopy and spectral analysis was identical to the native pentacylindrical pbs core domain. each cylinder of the central tricylindric unit was comprised of four ap (alphabeta)3 disks. mass analysis using the scanning transmission electron microscope (stem) s ... | 1998 | 9571058 |
| molecular and genetic analysis of two closely linked genes that encode, respectively, a protein phosphatase 1/2a/2b homolog and a protein kinase homolog in the cyanobacterium anabaena sp. strain pcc 7120. | reversible protein phosphorylation plays important roles in signal transduction. one gene, prpa, encoding a protein similar to eukaryotic types of phosphoprotein phosphatases pp1, pp2a, and pp2b, was cloned from the nitrogen-fixing cyanobacterium anabaena sp. strain pcc 7120. interestingly, a eukaryotic-type protein kinase gene, pkne, was found 301 bp downstream of prpa. this unusual genetic arrangement provides the opportunity for study about how the balance between protein phosphorylation and ... | 1998 | 9573144 |
| studies on the phytoplankton populations and physico-chemical conditions of treated sewage discharged into lake manzala in egypt. | over a full year, the phytoplankton populations and physico-chemical conditions of treated sewage discharged into lake manzala in egypt were investigated. sixty-seven species of algae were identified, 18 cyanophyta (cyanobacteria), 19 chlorophyta, 21 bacillariophyta, 6 euglenophyta, 2 cryptophyta and one species pyrrhophyta. nitzschia (6 spp.), scenedesmus (6 spp.), navicula (4 spp.), oscillatoria (4 spp.) and euglena (4 spp.) were the most common genera. a remarkable seasonal variation in speci ... | 1998 | 9579343 |
| acquisition of a new type of fructose-1,6-bisphosphatase with resistance to hydrogen peroxide in cyanobacteria: molecular characterization of the enzyme from synechocystis pcc 6803. | we have previously described that synechococcus pcc 7942 cells contain two fructose-1,6-bisphosphatase isozymes, designated f-i and f-ii the former belongs to a new type of fructose-1,6-bisphosphatase, while the latter is a typical enzyme similar to the cytosolic and chloroplastic forms from eukaryotic cells [tamoi et al., arch. biochem. biophys., 334, 1996, 27-36]. the genes of f-i and f-ii were found in three species of cyanobacteria, synechocystis pcc 6803, anabaena 7120, and plectonema borya ... | 1998 | 9602137 |
| cloning and characterisation of the pknd gene encoding an eukaryotic-type protein kinase in the cyanobacterium anabaena sp. pcc7120. | protein phosphorylation catalysed by protein kinases is an important mechanism for signal transduction in both prokaryotes and eukaryotes. a novel gene, pknd, encoding a protein similar to eukaryotic-type protein kinases, was cloned from anabaena sp. pcc7120. the n-terminal region of pknd is 60% identical to that of pkna, another putative ser/thr kinase from the same strain. both pkna and pknd have c-terminal regions that are rich in pro and thr residues. expression of pknd was undetectable by r ... | 1998 | 9613569 |
| first identification of microcystins in irish lakes aided by a new derivatisation procedure for electrospray mass spectrometric analysis. | recent animal and bird deaths at several lakes in ireland were indicative of possible cyanobacterial poisoning. using protein phosphatase inhibition assays, microcystins (mcs) were identified in extracts of cyanobacteria from several lakes at concentrations ranging from 1.6 to 168 micrograms/g. this is the first report of mcs in irish freshwaters. the protein phosphatase inhibition assay was used to screen fractions during hplc purification of the mcs in cyanobacteria (anabaena and oscillatoria) ... | 1997 | 9615313 |
| targeting and modification of prokaryotic cell-cell junctions by tobacco mosaic virus cell-to-cell movement protein. | the movement protein (mp) of tobacco mosaic virus (tmv) facilitates the cell-to-cell spread of infection by altering the structure and function of plasmodesmata, the intercellular communication channels in plants. because the protein was shown to interfere with intercellular communication when expressed in the cyanobacterium anabaena sp. strain pcc 7120, whether the ability of the protein to target and to modify intercellular communication channels in plants is conserved in this prokaryote was i ... | 1998 | 9628027 |
| action of the allelochemical, fischerellin a, on photosystem ii. | the cyanobacterium, fischerella muscicola, produces a secondary metabolite named fischerellin a (fs) that strongly inhibits the growth of cyanobacteria and other photosynthetic organisms. the compound exhibits a unique structure and is composed of two cyclic amines and a c15 substituent that contains a double bond in the (z) configuration and two triple bonds [l. hagmann, f. jüttner, tetrahedron lett., 37 (1996) 6539-6542]. the site of fs action is located in photosystem ii (psii). the chlorophy ... | 1998 | 9630706 |
| multiple oligomeric forms of glucose-6-phosphate dehydrogenase in cyanobacteria and the role of opca in the assembly process. | multiple molecular forms of glucose-6-phosphate dehydrogenase (g6pdh) were detected by activity staining in non-denaturing polyacrylamide gels of cell-free extracts from a range of cyanobacteria including anabaena sp. pcc 7120, synechococcus sp. pcc 7942, plectonema boryanum pcc 73110, synechocystis sp. pcc 6803, nostoc sp. mac pcc 8009 and the marine strain synechococcus sp. wh7803. in most of the species tested, the profile of g6pdh activities was modulated by the growth of the cells in the pr ... | 1998 | 9639925 |
| pleiotropic effects of potassium deficiency in a heterocystous, nitrogen-fixing cyanobacterium, anabaena torulosa. | omission of potassium from the growth medium caused multiple metabolic impairments and resulted in cessation of growth of the filamentous, heterocystous, nitrogen-fixing cyanobacterium anabaena torulosa, during both diazotrophic and nitrogen-supplemented growth. prominent defects observed during potassium deprivation were: (i) the loss of photosynthetic pigments, (ii) impairment of photosynthetic functions, (iii) reduced synthesis of dinitrogenase reductase (fe-protein), (iv) inhibition of nitro ... | 1998 | 9639926 |
| dehydroradiosumin, a trypsin inhibitor from the cyanobacterium anabaena cylindrica. | dehydroradiosumin, a novel potent trypsin inhibitory dipeptide, was isolated from the freshwater cyanobacterium anabaena cylindrica (nies-19). its structure was elucidated as 1 on the basis of 2d nmr data and chemical degradation. the ic50 of 1 against trypsin was 0.1 microg/ml. | 1998 | 9644086 |
| molecular characterization of cyanophycin synthetase, the enzyme catalyzing the biosynthesis of the cyanobacterial reserve material multi-l-arginyl-poly-l-aspartate (cyanophycin). | cyanophycin (multi-l-arginyl-poly-l-aspartate), a water-insoluble reserve polymer of cyanobacteria, is a product of nonribosomal peptide synthesis. the purification of cyanophycin synthetase of the cyanobacterium anabaena variabilis is described. in sodium dodecylsulfate/polyacrylamide gel electrophoresis, the enzyme preparation shows one band with an apparent molecular mass of 100 kda. the native enzyme has an apparent molecular mass of approximately 230 kda, as determined by size-exclusion chr ... | 1998 | 9652408 |
| characterisation of an arabidopsis cdna encoding a thylakoid lumen protein related to a novel 'pentapeptide repeat' family of proteins. | we have cloned an arabidopsis cdna encoding a novel thylakoid lumen protein, p17.4, that has been previously isolated from lumen extracts of spinach chloroplasts. the protein is synthesised with a bipartite presequence containing a sec-type lumen-targeting signal peptide and the precursor protein is imported into the lumen of pea chloroplasts. the encoded protein is homologous to an anabaena protein that is essential for correct glycolipid localisation, and is also related to at least 16 unassig ... | 1998 | 9654141 |
| an electrochemical, kinetic, and spectroscopic characterization of [2fe-2s] vegetative and heterocyst ferredoxins from anabaena 7120 with mutations in the cluster binding loop. | residues within the cluster binding loops of plant-type [2fe-2s] ferredoxins are highly conserved and serve to structurally stabilize this unique region of the protein. we have investigated the influence of these residues on the thermodynamic reduction potentials and rate constants of electron transfer to ferredoxin:nadp+ reductase (fnr) by characterizing various single and multiple site-specific mutants of both the vegetative (vfd) and the heterocyst (hfd) [2fe-2s] ferredoxins from anabaena. in ... | 1998 | 9675025 |
| electrostatic contributions to the stability of halophilic proteins. | examination of the first crystal structures of proteins from a halophilic organism suggests that an abundance of acidic residues distributed over the protein surface is a key determinant of adaptation to high-salt conditions. although one extant theory suggests that acidic residues are favored because of their superior water-binding capacity, it is clear that extensive repulsive electrostatic interactions will also be present in such proteins at physiological ph. to investigate the magnitude and ... | 1998 | 9677300 |
| assessment of environmental conditions that favor hepatotoxic and neurotoxic anabaena spp. strains cultured under light limitation at different temperatures | | 1998 | 9688780 |
| evolutionary conserved light regulation of calvin cycle activity by nadph-mediated reversible phosphoribulokinase/cp12/ glyceraldehyde-3-phosphate dehydrogenase complex dissociation. | for higher plant chloroplasts, two key enzymes of the calvin cycle, phosphoribulokinase (ec 2.7.1.19) and glyceraldehyde-3-phosphate dehydrogenase (gapdh, ec 1.2.1.13), have recently been shown to be oligomerized onto the nonenzymatic peptide cp12. enzymatic activity depends on complex dissociation, mediated by nadph. the discovery of genes for cp12 in mosses, green algae, and cyanobacteria, together with the analysis of equivalent multiprotein complexes of chlamydomonas and synechocystis sugges ... | 1998 | 9689144 |
| morphological differentiation and nitrogen fixation in transposon generated mutants of anabaena 7120. | mutants having partially repressed glutamine sythetase (transferase) activity and high nitrogenase activity were isolated following transposon mutagenesis. two of these mutants m11 and m73 showed a decrease in heterocyst frequency compared with the wild type strain. the level of the enzyme nitrogenase was much higher in all the mutant strains. nitrate and ammonia completely suppressed heterocyst differentiation and nitrogenase activity in mutants m11 and m73, but mutant m55 differentiated hetero ... | 1997 | 9693878 |
| a transposition-induced mutant of nostoc ellipsosporum implicates an arginine-biosynthetic gene in the formation of cyanophycin granules and of functional heterocysts and akinetes. | in strain ne1 of tn5-1058-mutagenized nostoc ellipsosporum, the transposon was found within a gene whose translation product is similar in amino acid sequence to the arginine-biosynthetic protein n-acetylglutamate semialdehyde dehydrogenase encoded by argc of bacillus subtilis. the argc reported from anabaena sp. strain pcc 7120 hybridized to a sequence different from the one interrupted by the transposon in ne1. the newly identified gene from n. ellipsosporum was denoted argl. the argl mutation ... | 1998 | 9695912 |
| regulation of hepa of anabaena sp. strain pcc 7120 by elements 5' from the gene and by hepk. | in anabaena spp., synthesis of the heterocyst envelope polysaccharide, required if the cell is to fix dinitrogen under aerobic conditions, is dependent on the gene hepa. a transcriptional start site of hepa was localized 104 bp 5' from its translational initiation codon. a 765-bp open reading frame, denoted hepc, was found farther upstream. inactivation of hepc led to constitutive expression of hepa and prevented the synthesis of heterocyst envelope polysaccharide. however, the glycolipid layer ... | 1998 | 9696774 |
| adp-glucose pyrophosphorylase from potato tubers. site-directed mutagenesis studies of the regulatory sites. | several lysines (lys) were determined to be involved in the regulation of the adp-glucose (glc) pyrophosphorylase from spinach leaf and the cyanobacterium anabaena sp. pcc 7120 (k. ball, j. preiss [1994] j biol chem 269: 24706-24711; y. charng, a.a. iglesias, j. preiss [1994] j biol chem 269: 24107-24113). site-directed mutagenesis was used to investigate the relative roles of the conserved lys in the heterotetrameric enzyme from potato (solanum tuberosum l.) tubers. mutations to alanine of lys- ... | 1998 | 9733546 |