Publications

the essential escherichia coli msba gene, a multicopy suppressor of null mutations in the htrb gene, is related to the universally conserved family of atp-dependent translocators.	we report the characterization of the msba gene, isolated as a multicopy suppressor of the htrb temperature-sensitive phenotype. the msba gene maps to 20.5 min on the escherichia coli genetic map and encodes a protein with an estimated molecular mass of 64,460 da, with the properties of an integral membrane protein. the amino acid sequence of msba is very similar to those of the family of atp-dependent translocators, which includes the haemolysin b protein of e. coli and the mammalian multidrug ...	1993	8094880
high-resolution mapping of genetic loci of anabaena pcc 7120 required for photosynthesis and nitrogen fixation.	a physical map of the anabaena genome permitted the localization of its genes to chromosomal fragments generated by rarely cutting restriction endonucleases and separated by pulsed-field gel electrophoresis. we introduce a novel means of mapping more precisely to c. 20 kb by use of rare restriction sites within vectors bearing cloned sequences that undergo homologous recombination with the genome. we thereby localize and orient genes encoding principal photosynthetic pigments. the relative spaci ...	1993	8098839
genes for two subunits of acetyl coenzyme a carboxylase of anabaena sp. strain pcc 7120: biotin carboxylase and biotin carboxyl carrier protein.	genes for two subunits of acetyl-coenzyme a carboxylase, biotin carboxylase and biotin carboxyl carrier protein, have been cloned from anabaena sp. strain pcc 7120. the two proteins are 181 and 447 amino acids long and show 40 and 57% identity to the corresponding escherichia coli proteins, respectively. the sequence of the biotinylation site in anabaena sp. strain pcc 7120 is metlysleu, not the metlysmet found in other sequences of biotin-dependent carboxylases. the amino acid sequence of bioti ...	1993	8102363
algal blooms in the spread and persistence of cholera.	cholera has been long associated with the seasonality of coastal algal blooms off bangladesh. using fluorescent antibody (fa) techniques, microbiologists have now identified a viable, non-cultivable form of vibrio cholerae in a wide range of marine life, including cyanobacteria (anabaena variabilis), diatoms (skeletonema costatum), phaeophytes (ascophyllum nodosum), in copepod molts, and in freshwater vascular aquatic plants (water hyacinths and duckweed). in unfavourable conditions v. cholerae ...	1993	8155853
hepatotoxin (microcystin) and neurotoxin (anatoxin-a) contained in natural blooms and strains of cyanobacteria from japanese freshwaters.	amounts of hepatotoxic microcystin and neurotoxic anatoxin-a were estimated in natural blooms and strains of cyanobacteria from freshwaters in japan. a simultaneous analysis method of anatoxin-a and microcystin was applied to natural bloom samples, which has been dominated by several species and the strains of cyanobacteria which produced simultaneously both toxins. the natural blooms examined in the present study were mainly composed of anabaena and oscillatoria, but most also contained microcy ...	1993	8167957
response of the cyanobacterium anabaena doliolum to endosulfan toxicity.	anabaena doliolum bhar. survived up to 3 mg/litre endosulfan on agar plates. inhibition was visible from the beginning of growth at all tested concentrations; the lc50 was 2.15 +/- 0.07 mg/l (p = 0.05). though the growth and pigment inhibition at concentrations < 1.0 mg/l was not significant, these were severe at all other tested concentrations (> or = 1.0 mg/l). the pesticide was detoxified by a. doliolum at concentrations of 1.5, 2.5, and 3.0 mg/l. the growth rates were more than 90% of the co ...	1993	8304005
an osmotic stress protein of cyanobacteria is immunologically related to plant dehydrins.	dehydrins are a family of desiccation proteins that were identified originally in plants (t.j. close, a.a. kortt, p.m. chandler [1989] plant mol biol 13: 95-108; g. galau, t.j. close [1992] plant physiol 98: 1523-1525). dehydrins are characterized by the consensus amino acid sequence domain ekkgimdkikeklpg found at or near the carboxy terminus; the core of this domain (kikeklpg) may be repeated from one to many times within the complete polypeptide. dehydrins generally accumulate in plants in re ...	1993	8310057
molecular structure of the oxidized, recombinant, heterocyst [2fe-2s] ferredoxin from anabaena 7120 determined to 1.7-a resolution.	the [2fe-2s] ferredoxin produced in the heterocyst cells of anabaena 7120 plays a key role in nitrogen fixation, where it serves as an electron acceptor from various sources and an electron donor to nitrogenase. the three-dimensional structure of this ferredoxin has now been determined and refined to a crystallographic r value of 16.7%, with all measured x-ray data from 30.0 to 1.7 a. the molecular motif of this ferredoxin is similar to that of other plant-type ferredoxins with the iron-sulfur c ...	1993	8329401
purification and properties of a flavodoxin from the heterocystous cyanobacterium anabaena sphaerica.	a flavodoxin was purified to homogeneity from the nitrogen-fixing heterocystous cyanobacterium anabaena sphaerica grown under iron-limited conditions. the protein has a molecular mass of 21 kda, and its spectral properties and amino-acid composition are very close to that of flavodoxins from other cyanobacteria. a. sphaerica flavodoxin supported the activities of a. sphaerica nadp reductase and clostridium butyricum hydrogenase in reconstituted systems with illuminated plant chloroplasts as redu ...	1993	8343530
homology of the n-terminal domain of the peth gene product from anabaena sp. pcc 7119 to the cpcd phycobilisome linker polypeptide.	the complete nucleotide sequence of the peth gene encoding ferredoxin-nadp+ reductase from the nitrogen-fixing cyanobacterium anabaena sp. pcc 7119 has been determined. the encoded polypeptide is 136 amino acids longer than the enzyme obtained after purification to homogeneity. the extended n-terminal domain consists of 80 amino acids which shows homology to the cpcd phycobilisome linker polypeptide, through which fnr might be anchored to the thylakoid-bound phycobilisomes. a 56 amino acid inter ...	1993	8343609
self-splicing of the group i intron from anabaena pre-trna: requirement for base-pairing of the exons in the anticodon stem.	in the cyanobacterium anabaena, the precursor to trna(leu) has a 249-nucleotide group i intron inserted between the wobble and second bases of the anticodon; the intron self-splices during transcription in vitro [xu, m. q., kathe, s. d., goodrich-blair, h., nierzwicki-bauer, s. a., & shub, d. a. (1990) science 250, 1566-1570]. by studying splicing of isolated pre-trna, we confirm that splicing occurs by the two-step transesterification mechanism characteristic of group i introns, resulting in ex ...	1993	8347600
physical genome map of the unicellular cyanobacterium synechococcus sp. strain pcc 7002.	a physical restriction map of the genome of the cyanobacterium synechococcus sp. strain pcc 7002 was assembled from asci, noti, sali, and sfii digests of intact genomic dna separated on a contour-clamped homogeneous electric field pulsed-field gel electrophoresis system. an average genome size of 2.7 x 10(6) bp was calculated from 21 noti, 37 sali, or 27 sfii fragments obtained by the digestions. the genomic map was assembled by using three different strategies: linking clone analysis, pulsed-fi ...	1993	8349551
identification of the nifj gene coding for pyruvate: ferredoxin oxidoreductase in dinitrogen-fixing cyanobacteria.	a 329 bp dna segment from both anabaena variabilis and anabaena pcc 7119 was amplified using the polymerase chain reaction (pcr). the sequences from the two cyanobacteria showed strong similarities to the corresponding part of the nifj gene from klebsiella pneumoniae and enterobacter agglomerans. the present findings underline earlier results of enzymatic studies that heterocystous cyanobacteria possess a pyruvate:ferredoxin (flavodoxin) oxidoreductase (pfo). the nifj gene segment could not be d ...	1993	8352652
general distribution of the nitrogen control gene ntca in cyanobacteria.	the ntca gene from synechococcus sp. strain pcc 7942 encodes a regulatory protein which is required for the expression of all of the genes known to be subject to repression by ammonium in that cyanobacterium. homologs to ntca have now been cloned by hybridization from the cyanobacteria synechocystis sp. strain pcc 6803 and anabaena sp. strain pcc 7120. sequence analysis has shown that these ntca genes would encode polypeptides strongly similar (77 to 79% identity) to the synechococcus ntca prote ...	1993	8366058
amino acid residues in anabaena ferredoxin crucial to interaction with ferredoxin-nadp+ reductase: site-directed mutagenesis and laser flash photolysis.	ferredoxin (fd) functions in photosynthesis to transfer electrons from photosystem i to ferredoxin-nadp+ reductase (fnr). we have made several site-directed mutants of anabaena 7120 fd and have used laser flash photolysis to investigate the effects of these mutations on the kinetics of reduction of oxidized fd by deazariboflavin semiquinone (drfh.) and the reduction of oxidized anabaena fnr by reduced fd. none of the mutations influenced the second-order rate constant for drfh. reduction by more ...	1993	8369305
pulse radiolysis and related studies on the ru-modified his 16 derivative of anabaena variabilis [2fe-2s] ferredoxin.	the preparation and characterisation of a ru-modified derivative of the [2fe-2s] ferredoxin fdi component of a. variabilis by attachment of ru(nh3)5 to a surface histidine has been carried out. metal analyses by icp gave an fe/ru ratio of 1.97:1. from nmr the attachment is confirmed as a modification at his-16 and not his-92. no ru-modification of the [2fe-2s] fdi component of spinach, which has his-92 but no his-16, was observed. histidine pka values have been determined and anomalously low val ...	1993	8373814
paralytic shellfish poisons from freshwater blue-green algae.		1993	8377696
evidence for a chimeric nature of nuclear genomes: eubacterial origin of eukaryotic glyceraldehyde-3-phosphate dehydrogenase genes.	higher plants process two distinct, nuclear gene-encoded glyceraldehyde-3-phosphate dehydrogenase (gapdh) proteins, a calvin-cycle enzyme active within chloroplasts and a glycolytic enzyme active within the cytosol. the gene for the chloroplast enzyme was previously suggested to be of endosymbiotic origin. since the ancestors of plastids were related to cyanobacteria, we have studied gapdh genes in the cyanobacterium anabaena variabilis. our results confirm that the nuclear gene for higher plant ...	1993	8378350
is1136, an insertion element in the erythromycin gene cluster of saccharopolyspora erythraea.	the saccharopolyspora erythraea eryai and eryaii genes, which, together with eryaiii, are responsible for the formation of the macrolactone portion of the antibiotic erythromycin, are separated by a 1.46-kb segment, designated is1136, with the characteristics of an insertion sequence. it contains an open reading frame of 425 codons similar to that of the anabaena is891 and is present in four nonidentical copies in the sac. erythraea genome. inverted repeats were found near the ends of is1136, an ...	1993	8386127
purification and properties of a bacterial-type ferredoxin from the nitrogen-fixing cyanobacterium anabaena variabilis atcc29413.	three soluble ferredoxins were purified to homogeneity from nitrogen-fixing cultures of anabaena variabilis (atcc 29413) and characterized. the purified proteins have different absorption spectra, molecular mass, iron content, amino-acid composition and resistance to o2 inactivation. two were plant-type ferredoxins fdi and fdxh, corresponding to the previously reported ferredoxins ii and i (böhme, h. and schrautemeier, b. (1987) biochim. biophys. acta 891, 1-7). the third ferredoxin (ferredoxin ...	1993	8387824
isolation of a delta 6-desaturase gene from the cyanobacterium synechocystis sp. strain pcc 6803 by gain-of-function expression in anabaena sp. strain pcc 7120.	the enzyme delta 6-desaturase is responsible for the conversion of linoleic acid (18:2) to gamma-linolenic acid (18:3 gamma). a cyanobacterial gene encoding delta 6-desaturase was cloned by expression of a synechocystis genomic cosmid library in anabaena, a cyanobacterium lacking delta 6-desaturase. expression of the synechocystis delta 6-desaturase gene in anabaena resulted in the accumulation of gamma-linolenic acid (gla) and octadecatetraenoic acid (18:4). the predicted 359 amino acid sequenc ...	1993	8389613
anabaena sp. strain pcc 7120 bifa gene encoding a sequence-specific dna-binding protein cloned by in vivo transcriptional interference selection.	vf1 is a dna-binding protein from the cyanobacterium anabaena sp. strain pcc 7120. vf1 was originally identified on the basis of its binding affinity to the upstream region of xisa, which encodes a heterocyst-specific site-specific recombinase. vf1 also binds to the glna, rbcl, and nifh promoters in vitro, suggesting that vf1 interacts with genes expressed in both vegetative cells and heterocysts. the role of vf1 in regulating gene expression in pcc 7120 is unknown. as a step towards the goal of ...	1993	8391534
iron-dependent protection of the synechococcus ferredoxin i transcript against nucleolytic degradation requires cis-regulatory sequences in the 5' part of the messenger rna.	we have previously reported that the ferredoxin i gene from synechococcus sp. pcc 7942 is regulated by iron at the level of differential mrna stability. to identify iron-responsive elements in the synechococcus ferredoxin transcript, we have tested chimaeric constructs containing translational fusions between the synechococcus and the anabaena sp. pcc 7937 ferredoxin genes for iron-dependent expression in transgenic synechococcus strains. this strategy was based on the observation that the level ...	1993	8400125
genetic diversity and phylogeny analysis of azolla based on dna amplification by arbitrary primers.	the polymerase chain reaction was used to amplify random sequences of dna from 25 accessions of azolla to evaluate the usefulness of this technique for identification and phylogenetic analysis of this aquatic fern. accessions were selected to represent all known species within the genus azolla and to encompass the world-wide distribution of the fern. primers of 10 nucleotides with 70% g + c content were used to generate randomly amplified polymorphic dna from the symbiotic azolla-anabaena comple ...	1993	8405985
characterization of genes for an alternative nitrogenase in the cyanobacterium anabaena variabilis.	anabaena variabilis atcc 29413 is a heterotrophic, nitrogen-fixing cyanobacterium that has been reported to fix nitrogen and reduce acetylene to ethane in the absence of molybdenum. dna from this strain hybridized well at low stringency to the nitrogenase 2 (vnfdgk) genes of azotobacter vinelandii. the hybridizing region was cloned from a lambda embl3 genomic library of a. variabilis, mapped, and sequenced. the deduced amino acid sequences of the vnfd and vnfk genes of a. variabilis showed only ...	1993	8407800
spatial expression and autoregulation of hetr, a gene involved in the control of heterocyst development in anabaena.	the spatially patterned differentiation of heterocysts in the filamentous cyanobacterium anabaena requires a functional hetr gene. transcriptional fusions to luxab show that hetr is transcribed at a low level throughout the filament when anabaena is grown with combined nitrogen, and that induction of the gene begins within 2 h following nitrogen deprivation. by 3.5 h, induction is localized to spaced foci. by 6 h, there is an overall induction of at least threefold in whole cultures, reflecting ...	1993	8412673
evidence from directed mutagenesis that positively charged amino acids are necessary for interaction of nitrogenase with the [2fe-2s] heterocyst ferredoxin (fdxh) from the cyanobacterium anabaena sp., pcc7120.	sequence comparison of the heterocyst-type ferredoxin (fdxh) from anabaena 7120 and type-1 ferredoxins (petf) from the same organism and other cyanobacteria revealed a group of positively charged residues characteristic for fdxh. molecular modeling showed that these basic amino acids are clustered on the surface of fdxh. the corresponding domain of petf contained acidic or nonpolar residues instead. to identify amino acids that are important for interaction with nitrogenase, we generated site-di ...	1993	8413197
growth of the cyanobacterium anabaena on molecular nitrogen: nifj is required when iron is limited.	the nifj gene of klebsiella pneumoniae encodes an oxidoreductase required for the transfer of electrons from pyruvate to flavodoxin, which reduces nitrogenase. the nifj gene of anabaena 7120, isolated from a cosmid bank, was found to contain an open reading frame encoding a 1197-aa protein. the deduced amino acid sequence shows 50% identity to the klebsiella homolog. the nifj gene in anabaena 7120 was inactivated by chromosomal interruption. the resulting mutant was unable to grow on medium depl ...	1993	8415612
15n- and 13c-labeled media from anabaena sp. for universal isotopic labeling of bacteriocins: nmr resonance assignments of leucocin a from leuconostoc gelidum and nisin a from lactococcus lactis.	a procedure for universal 13c and/or 15n labeling of microbial peptides which are produced by fermentation in complex media and its application to two food-preserving bacteriocins from lactic acid bacteria are described. isotopic enrichment of nisin a (from lactococcus lactis) and of leucocin a (from leuconostoc gelidum) is readily achieved using a soluble peptone derived from enzymatic hydrolysis (pepsin and chymopapain) of anabaena sp. atcc 27899 cells grown on sodium [13c]bicarbonate and/or s ...	1993	8418850
cloning and nucleotide sequence of the gene for dinitrogenase reductase (nifh) from the heterocyst-forming cyanobacterium anabaena sp. l31.	the nucleotide sequence of an 1655 base pair segment from anabaena sp. l31 containing the 3' half of the nifu gene, the complete sequence of the nifh gene and the 5' end of the nifd gene is presented. nifh is very highly conserved with the same gene from anabaena sp. pcc 7120 (91% identical at the nucleotide level; 94% identical at the amino acid level) as are nifu and nifd. the intergenic regions are less well conserved.	1993	8424961
dna amplification fingerprinting of the azolla-anabaena symbiosis.	the azolla-anabaena symbiosis has been used for centuries as a nitrogen biofertilizer in rice paddies. genetic improvement of the symbiosis has been limited by the difficulty in identifying azolla-anabaena accessions and anabaena azollae strains. the recently developed technique of dna amplification fingerprinting (daf) was applied to this problem. daf uses single, short, oligonucleotide primers of arbitrary sequence to direct amplification of a characteristic set of dna products by a thermostab ...	1993	8425061
facile sulfitolysis of the disulfide bonds in oxidized thioredoxin and glutaredoxin.	thioredoxins and glutaredoxins, in their oxidized form, possess a single disulfide bridge located on an edge of the small compact molecules. in contrast to most other disulfide-containing proteins, this s-s bridge is cleaved by millimolar concentrations of sulfite in the absence of protein denaturing agents at ph 7-8 and ambient temperature; however, the reaction is not quantitative. sulfitolysis of escherichia coli thioredoxin was found to be associated with an increase in fluorescence at 345 n ...	1993	8436120
the patb gene product, required for growth of the cyanobacterium anabaena sp. strain pcc 7120 under nitrogen-limiting conditions, contains ferredoxin and helix-turn-helix domains.	a mutant of anabaena sp. strain pcc 7120, called pat-2, that grows poorly under nitrogen-fixing conditions, has been isolated. the heterocysts of the mutant strain develop much more slowly than those of the wild type and are spaced more closely in an older culture of the mutant than in the wild type. the wild-type gene that complements the mutation in pat-2, called patb, was isolated and characterized. the predicted 529-amino-acid patb protein contains a region very similar to the fe4s4 bacteria ...	1993	8449877
iron-dependent stability of the ferredoxin i transcripts from the cyanobacterial strains synechococcus species pcc 7942 and anabaena species pcc 7937.	the effect of iron on ferredoxin i specific mrna levels was studied in the cyanobacterial strains synechococcus sp. pcc 7942 (anacystis nidulans r2) and anabaena sp. pcc 7937 (anabaena variabilis atcc 29413). in both strains addition of iron to iron-limited cells resulted in a rapid increase in ferredoxin mrna levels. to investigate the possible role of the ferredoxin promoter in iron regulation, a vector for promoter analysis in synechococcus pcc 7942 strain r2-pim9 was constructed, which conta ...	1993	8459769
amplified expression of a transcriptional pattern formed during development of anabaena.	the cyanobacterium anabaena responds to nitrogen deprivation by producing heterocysts, cells specialized for nitrogen fixation, at well-spaced intervals along its filaments. the gene hepa, required for heterocyst maturation, is expressed in response to nitrogen deprivation, prior to visible differentiation. a spatial pattern of hepa expression indistinguishable from the eventual pattern of heterocysts was made visible by fusing the hepa promoter to luxab, which encodes bacterial luciferase. beca ...	1993	8459770
the rubisco activase (rca) gene is located downstream from rbcs in anabaena sp. strain ca and is detected in other anabaena/nostoc strains.	a gene encoding ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) activase (rca) was found downstream from the rbclrbcs operon in the heterocystous cyanobacterium anabaena sp. strain ca. two unknown open reading frames were shown to be located between rbcs and rca in strain ca and all the genes, rbclrbcs, orf1, orf2, and rca were in the same transcriptional orientation. the deduced amino acid sequence of the anabaena rubisco activase showed both similarities and differences to the plant ...	1993	8467074
overproduction of anabaena 7120 ribulose-bisphosphate carboxylase/oxygenase in escherichia coli.	as a prerequisite to protein engineering, we have overexpressed the rbcls operon of the cyanobacterium anabaena 7120, in escherichia coli. the operon encodes the large and small subunits of ribulose-bisphosphate carboxylase/oxygenase (rubisco). levels of active enzyme exceed 6% of soluble protein. we noted an apparent third gene, an unidentified open reading frame (urf) referred to here as rbcx, in the 558-bp intergenic space between the large and small subunit encoding genes. the urf, rbcx, has ...	1993	8472962
nontarget effects of carbaryl and its hydrolysis product, 1-naphthol, towards anabaena torulosa.	the toxic effects of carbaryl and its hydrolysis product, 1-naphthol, singly and in combination, towards a filamentous diazotrophic cyanobacterium, anabaena torulosa, were determined. the toxicity criteria employed, viz., packed cell volume, chlorophyll a, phycocyanin, carotenoids, heterocyst differentiation and nitrogen fixation, were greatly affected by the toxicants above 25 micrograms/ml concentrations. however, 1-naphthol was more toxic to the diazotroph than was carbaryl. the toxicity was ...	1993	8490578
a comparative laser-flash absorption spectroscopy study of anabaena pcc 7119 plastocyanin and cytochrome c6 photooxidation by photosystem i particles.	laser-flash absorption spectroscopy has been used to investigate the kinetics of electron transfer from reduced cytochrome c6 and plastocyanin, isolated from anabaena pcc 7119, to oxidized p700 in photosystem-i particles isolated from the same cyanobacterium and from spinach. for all metalloproteins and photosystems, the observed rate constant has a non-linear protein-concentration dependence, thus suggesting complex formation preceding electron transfer. plastocyanin and cytochrome c6 have simi ...	1993	8504808
on the activation mechanism of the h(+)-atp synthase and unusual thermodynamic properties in the alkalophilic cyanobacterium spirulina platensis.	the activation requirements and thermodynamic characteristics of atp synthase from the alkalophilic cyanobacterium spirulina platensis were studied in coupled membrane vesicles. activation by methanol increased the vmax, while the km for mgatp was unaffected (0.7 mm). we propose that in sp. platensis, as in chloroplasts, the activating effect of methanol is based on perturbation of the gamma-epsilon subunit interaction. light-driven atp synthesis by membrane vesicles of sp. platensis was stimula ...	1993	8504834
experimental approaches for detecting self-splicing group i introns.		1993	7505383
a gene encoding a protein related to eukaryotic protein kinases from the filamentous heterocystous cyanobacterium anabaena pcc 7120.	protein kinases play essential roles in the development of eukaryotic cells. these enzymes display various degrees of sequence similarity in their catalytic domains. this conservation has allowed the identification of protein kinases in a variety of organisms, including the gram-negative bacterium myxococcus xanthus. in this study, sequences related to those encoding eukaryotic protein kinases were amplified by pcr from dna of anabaena pcc 7120, a filamentous cyanobacterium that differentiates c ...	1993	7505448
analysis of gas vesicle gene expression in haloferax mediterranei reveals that gvpa and gvpc are both gas vesicle structural proteins.	gas vesicle synthesis in haloferax mediterranei involves several gene products encoded by a 9.4-kilobase pair dna region (mc-vac region) that contains 13 genes in addition to gvpa encoding the major structural gas vesicle protein. the expression of part of this region, encompassing the genes gvpa, gvpc, gvpn, and gvpo was investigated. these genes are transcribed from a common promoter located upstream of gvpa. transcripts of 0.34 (gvpa only), 1.8 (gvpa/c), 2.4 (gvpa/c/n) and 3 kilobases (gvpa/c ...	1993	7683649
in situ detection of transcripts for ribulose-1,5-bisphosphate carboxylase in cyanobacterial heterocysts.	heterocysts of free-living cyanobacteria lack ribulose-1,5-bisphosphate carboxylase activity. nevertheless, using in situ hybridizations, we demonstrate that transcripts for the rbcl and rbcs genes are present in both heterocysts and vegetative cells of anabaena spp. in association with, or isolated from, the azolla-anabaena symbiosis. in contrast, rbcls transcripts were detected only in vegetative cells of the free-living cyanobacterium anabaena strain 7120. under anaerobic growth conditions th ...	1993	7693657
expression of glna in the cyanobacterium synechococcus sp. strain pcc 7942 is initiated from a single nif-like promoter under various nitrogen conditions.	the glna mrna, encoding glutamine synthetase, is differentially accumulated in the cyanobacterium synechococcus sp. strain pcc 7942 in media containing different nitrogen sources. with the different nitrogen compounds, transcription of glna initiated at a single site located -146 nucleotides upstream of the translation start site of the gene. a similarity of the nif-like promoter of the glna gene of anabaena sp. strain pcc 7120 and a binding-site sequence for the synechococcus sp. strain pcc 794 ...	1993	7902350
targeted interruption of the psaa and psab genes encoding the reaction-centre proteins of photosystem i in the filamentous cyanobacterium anabaena variabilis atcc 29413.	the two reaction-centre proteins of the photosystem i (psi) complex are encoded by two adjacent genes named psaa and psab. we have performed targeted mutagenesis to insertionally inactivate each of these genes in the filamentous cyanobacterium anabaena variabilis atcc 29413. the resulting mutant strains, termed psaa::nmr and psab::nmr, were blue because of a high ratio of phycobilin to chlorophyll and were unable to grow in light. these mutant cells also lacked chemically reducible p700 (the rea ...	1993	7934924
dark heterotrophic growth conditions result in an increase in the content of photosystem ii units in the filamentous cyanobacterium anabaena variabilis atcc 29413.	the filamentous nitrogen-fixing cyanobacterium anabaena variabilis atcc 29413 is capable of heterotrophic growth in complete darkness. after 6 months of continuous dark growth, both the autotrophic and heterotrophic cultures were found to have the same doubling time of 14 h. on a cellular basis, the chlorophyll content remained the same and the phycobilin content showed an increase in the dark-grown cultures. fluorescence emission spectra at 77 k of dark-grown cells indicated that the phycobilis ...	1993	8022943
[aspartate kinase activity of cyanobacteria anabaena variabilis].	aspartate-kinase (ask) activity of filamentous cyanobacteria a. variabilis and its dependence on physico-chemical factors and substrate concentration in the reaction mixture have been studied. three isoenzymes ask-1, ask-2 and ask-3 which differ in the values of ph-optima, molecular weight, isoelectric points and effector of retro-inhibition have been isolated by ion-exchange chromatography. high level of inhibition of summary ask of the cell-free extract can be reached only in a case of simulta ...	1993	8048183
dissolved nitrogen uptake by a cyanobacterial bloom (anabaena flos-aquae) in a subarctic lake.	uptake of dissolved nitrogen (nh(4) + no(3) + urea + n(2)) by a cyanobacterial [anabaena flos-aquae (lyngb.)] de brèb population in smith lake, alaska, was measured every 2 to 4 days during the spring of 1990. total dissolved nitrogen uptake ranged from 0.34 to 24.75 mumol liter h, with a mean of 5.75 mumol liter h; the euphotic zone accounted for 91% of the uptake. the mean turnover time for dissolved combined nitrogen (nh(4) + no(3) + urea) in the euphotic zone was less than 14 h, and that for ...	1993	16348867
differential responses of nitrogen-fixing cyanobacteria to salinity and osmotic stresses.	two nitrogen-fixing anabaena strains were found to be differentially tolerant to salinity and osmotic stresses. anabaena torulosa, a brackish-water, salt-tolerant strain, was relatively osmosensitive. anabaena sp. strain l-31, a freshwater, salt-sensitive strain, on the other hand, displayed significant osmotolerance. salinity and osmotic stresses affected nitrogenase activity differently. nitrogen fixation in both of the strains was severely inhibited by the ionic, but not by the osmotic, compo ...	1993	16348897
the algal community as an indicator of the trophic status of lake patzcuaro, mexico.	an evaluation of water quality and phytoplankton composition position was carried out in order to determine the trophic conditions of lake patzcuaro (2035 m above sea level), a high altitude tropical lake. temperatures ranged from 15 to 23 degrees c. total phosphorus and inorganic nitrogen showed a seasonal variation; highest values coincided with the rainy season (0.48 and 2.1 mg litre(-1), respectively). dissolved oxygen ranged from 2 to 7.9 mg litre(-1) at the surface and from 0.6 to 7.3 mg l ...	1993	15091845
surfactant-induced hydrogen production in cyanobacteria.	addition of tween 85 to aqueous suspensions of anabaena variabilis induced photosynthetic evolution of hydrogen over a time span of several weeks: as much as 148 nmol h(2)/h . mg dry weight was produced in the first week by a suspension containing 4.2 mg dry weight of cells and 77 mm tween 85. the chemical structure of tween 85 was a necessary prerequisite for inducing hydrogen production, as compounds such as tween 20, 60, and 80 had a quite different effect. there was a coupling between photos ...	1993	18613150
codon usage adaptation in the ferredoxin-nadp+ oxidoreductase of cyanophora paradoxa upon translocation from cyanoplast to nucleus.	previous investigations of the peth gene of the biflagellated autotrophic protist cyanophora paradoxa (cp; glaucocystophyta), descendant of an original endocyanome (symbiotic consortium of a eukaryote with an endocytobiotic cyanobacterium), established that: (i) the gene coding for a cyanoplast protein (fnr) is located on the nuclear genome; (ii) the sequence of the mature protein shows a high degree of amino-acid conservation to cyanobacterial homologs; (iii) the sequence of the transit peptide ...	1994	8063096
analysis of the sequences within and flanking the cyanoglobin-encoding gene, glbn, of the cyanobacterium nostoc commune utex 584.	a 3.5-kb segment of dna containing nifu glbn nifh nifd was cloned from a gene library of nostoc 584 and sequenced. the nifu-glbn intergenic region contains short tandemly repeated repetitive sequences (5'-aattacg). a sequence corresponding to a nifa-like upstream activator sequence (with the consensus recognition sequence for bifa in anabaena 7120), elements of a nifh promoter and a sequence that may function as a transcription terminator, were identified downstream from glbn. glbn, unique to ce ...	1994	8063099
a third genetic locus required for the formation of heterocysts in anabaena sp. strain pcc 7120.	mutagenesis of anabaena sp. strain pcc 7120 with a derivative of transposon tn5 led to the isolation of a mutant strain, p6, in which heterocysts are not formed (a. ernst, t. black, y. cai, j.-m. panoff, d. n. tiwari, and c. p. wolk, j. bacteriol. 174:6025-6032, 1992). reconstruction of the transposon mutation of p6 in the wild-type strain reproduced the phenotype of the original mutant. analysis by pulsed-field gel electrophoresis localized the transposition at ca. 3.44 mb on the physical map o ...	1994	8071202
identification of a nuclease and host restriction-modification in the unicellular, aerobic nitrogen-fixing cyanobacterium cyanothece sp.	in the process of developing a gene transfer system for the marine, unicellular, nitrogen-fixing cyanobacterium cyanothece sp. strain bh68k, two major restriction barriers have been identified. a cell wall-associated nuclease exhibited non-site-specific degradation of covalently closed circular and linear double-stranded dna molecules, including cyanothece sp. strain bh68k chromosomal dna. the nuclease is easily released from intact cells by using water or buffer containing triton x-100. nucleas ...	1994	8071241
electron paramagnetic resonance as a tool for monitoring overexpression in escherichia coli of fully functional flavodoxin.	overexpression of foreign proteins in escherichia coli is usually tested by sodium dodecyl sulfate-polyacrylamide gel electrophoresis or western blot analysis. however, when metalloproteins of flavoenzymes are expressed, the correct assembly of the polypeptide chain to the cofactor cannot be verified using these methods. we have used epr spectroscopy and mancini tests to monitor the expression of holoflavodoxin from the cyanobacteria anabaena in e. coli. flavodoxin from anabaena sp pcc 7119 was ...	1994	8074277
a role for osmotic stress-induced proteins in the osmotolerance of a nitrogen-fixing cyanobacterium, anabaena sp. strain l-31.	the molecular basis of tolerance to osmotic stress was investigated with a cyanobacterium, anabaena sp. strain l-31. the inherent osmotolerance of this strain (50% growth inhibition at 350 mm sucrose) was enhanced by adaptation with 100 mm sucrose for 30 min. addition of 10 mm kno3 during growth also conferred significant osmoprotection, but addition of 3 mm nh4cl did not. exposure of cells to 350 mm sucrose induced the expression of at least 12 osmotic-stress-induced proteins (osps) within 30 m ...	1994	8083182
cloning, sequencing and transcriptional studies of the genes for cytochrome c-553 and plastocyanin from anabaena sp. pcc 7120.	in some cyanobacteria and eukaryotic algae, cytochrome c-553 (c-552) and plastocyanin function as alternative electron carriers between the cytochrome b6-f complex and photosystem i. in these organisms plastocyanin is the electron carrier under copper-replete conditions, and cytochrome c-553 is the electron carrier during copper deprivation. in this paper we report the cloning, sequencing and transcriptional analysis of the genes for cytochrome c-553 and plastocyanin from anabaena sp. pcc 7120. ...	1994	8025680
structure-function studies of [2fe-2s] ferredoxins.	the ability to overexpress [2fe-2s] ferredoxins in escherichia coli has opened up exciting research opportunities. high-resolution x-ray structures have been determined for the wild-type ferredoxins produced by the vegatative and heterocyst forms of anabaena strain 7120 (in their oxidized states), and these have been compared to structural information derived from multidimensional, multinuclear nmr spectroscopy. the electron delocalization in in these proteins in their oxidized and reduced state ...	1994	8027024
further characterization by site-directed mutagenesis of the protein-protein interface in the ferredoxin/ferredoxin:nadp+ reductase system from anabaena: requirement of a negative charge at position 94 in ferredoxin for rapid electron transfer.	ferredoxins are small electron transfer proteins found ubiquitously in nature. in green plant photosynthesis, the soluble [2fe-2s] ferredoxin shuttles electrons from photosystem i to ferredoxin:nadp+ reductase. in order to define the features of the protein/protein interface required for efficient electron transfer from ferredoxin to ferredoxin:nadp+ reductase, we have made site-directed mutants of the ferredoxin from the cyanobacterium anabaena 7120 and measured the rate constants for electron ...	1994	8037461
expression of luxcd-e in anabaena sp. can replace the use of exogenous aldehyde for in vivo localization of transcription by luxab.	the genes luxcdabe from four luminescent bacteria suffice for light production in escherichia coli [meighen, microbiol. rev. 55 (1991) 123-142]. we have inserted these gene clusters between inverted polylinkers, and placed the resulting cassettes as reporters within derivatives of transposon tn5. anabaena sp. strain pcc 7120 was mutagenized with these transposons. the luminescence of all but the most highly self-luminescent resulting derivatives of anabaena sp. was strongly dependent on exogenou ...	1994	7959046
transcription control of ribulose bisphosphate carboxylase/oxygenase activase and adjacent genes in anabaena species.	the gene encoding ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) activase (rca) was uniformly localized downstream from the genes encoding the large and small subunits of rubisco (rbcl and rbcs) in three strains of anabaena species. however, two open reading frames (orf1 and orf2), situated between rbcs and rca in anabaena sp. strain ca, were not found in the intergenic region of anabaena variabilis and anabaena sp. strain pcc 7120. during autotrophic growth of anabaena cells, rca and ...	1994	7961423
transcriptional and translational analysis of ferredoxin and flavodoxin under iron and nitrogen stress in anabaena sp. strain pcc 7120.	in anabaena sp. strain pcc 7120, vegetative cell ferredoxin synthesis under iron starvation was repressed 25-fold, whereas heterocyst ferredoxin synthesis decreased only 2.8-fold. induction of flavodoxin under iron depletion was independent of the availability of combined nitrogen. under iron stress but in the presence of combined nitrogen, fdxh and nifh genes were transcriptionally active; although excision of the 11-kb element seemed to be completed, nitrogenase activity and the fdxh gene prod ...	1994	7961517
expression of anabaena pcc 7937 plastocyanin in synechococcus pcc 7942 enhances photosynthetic electron transfer and alters the electron distribution between photosystem i and cytochrome-c oxidase.	the pete gene encoding plastocyanin precursor protein from the cyanobacterium anabaena pcc 7937 was introduced in the cyanobacterial host strain synechococcus pcc 7942. the host normally only uses cytochrome c553 as photosystem i (ps i) donor. the heterologous gene was efficiently expressed using the inducible escherichia coli trc promoter. accumulation of plastocyanin protein depended on the presence of cu2+. the protein was accurately targeted to the thylakoid lumen, from which it could be iso ...	1994	7961743
laser flash-induced photoreduction of photosynthetic ferredoxins and flavodoxin by 5-deazariboflavin and by a viologen analogue.	laser flash photolysis has been used to compare the kinetics of reduction of ferredoxin isoforms from the green alga monoraphidium braunii, and the ferredoxin and flavodoxin from the cyanobacterium anabaena pcc 7119, by 5-deazariboflavin semiquinone (drfh.) and the viologen analogue 1,1'-propylene-2,2'-bipyridyl (pdq.+). similar ionic strength-independent second-order rate constants (1.4 x 10(8) m-1 s-1) were obtained for the reduction of both algal ferredoxin isoforms by drfh.. for the reductio ...	1994	7972374
the psac protein is necessary for the stable association of the psad, psae, and psal proteins in the photosystem i complex: analysis of a cyanobacterial mutant strain.	the psac protein binds two 4fe-4s centers, fa and fb, in the photosystem i (psi) protein complex. in the t398 strain of anabaena variabilis atcc 29413, the psac gene encoding this protein has been insertionally inactivated by the introduction of a neomycin resistance gene cartridge in the coding region. photosystem i complex was purified through native gel electrophoresis of beta-dodecyl maltoside solubilized thylakoid membranes from wild-type and t398 strains of anabaena 29413. the psi complex ...	1994	7979407
genetic evidence that hepa gene is involved in the normal deposition of the envelope of both heterocysts and akinetes in anabaena variabilis atcc 29413.	the hepa gene in anabaena sp. strain pcc 7120 is required for normal formation of the polysaccharide layer of the heterocyst envelope. a plasmid bearing hepa, interrupted by a neomycin-resistance cassette, was transferred by conjugation to wild type anabaena variabilis atcc 29413, so that the interrupted hepa gene replaced a homologous sequence. in the recombinant exconjugants, the envelopes of akinetes as well as of heterocysts were altered.	1994	7988900
[aspartate kinase complex of anabaena variabilis during the early period of development of cyanophage a-1].	aspartate kinase activity in cells of a. variabilis has been studied in the dynamics of development of virus infection. an early period of reproduction of cyanophage a-1 has been determined to be conjugated with the increase of biosynthesis of amino acids from aspartate family. five isoenzymes of aspartate kinase were isolated and purified from a. variabilis cells during early development period of cyanophage a-1. physicochemical properties and influence of amino acids of aspartate family on the ...	1994	7998339
role of alkali cations (k+ and na+) in cyanobacterial nitrogen fixation and adaptation to salinity and osmotic stress.	cyanobacteria occupy almost every possible ecological niche on earth, being tolerant to a large number of environmental stresses, including salinity and drought. many of them also fix atmospheric nitrogen. they are responsible for a significant share of biosolar energy conversions on this planet and make substantial contributions to the carbon and nitrogen status of both oceans and soils. sodium and potassium are two of the most prevalent cations on this planet. while k+ is an essential macronut ...	1994	8002008
characterization of deva, a gene required for the maturation of proheterocysts in the cyanobacterium anabaena sp. strain pcc 7120.	mutant m7, obtained by transposon mutagenesis of the cyanobacterium anabaena sp. strain pcc 7120, is impaired in the development of mature heterocysts. under aerobic conditions, the mutant is unable to fix n2 because of a deficiency of at least two components of the oxygen-protective mechanisms: a hemoprotein-coupled oxidative reaction and heterocyst-specific glycolipids. dna contiguous with the inserted transposon was recovered from the mutant and sequenced. the transposon had inserted itself w ...	1994	8002578
biosorption of nickel in complex aqueous waste streams by cyanobacteria.	a study was undertaken to determined if a suitable biosorbent could be found for removal of nickel at low concentrations (< 20 parts per million [ppm]) from a chemically complex wastewater effluent generated by electroplating operations. algae and cyanobacteria were chosen as candidate biosorbent materials because they are easy to grow and they have the ability to withstand processing into biosorbent materials. several species were screened for nickel-biosorption capacity initially, and three sp ...	1994	8010774
anatoxin-a and a previously unknown toxin in anabaena planctonica from blooms found in lake mulargia (italy).	algal extracts of anabaena planctonica from lake mulargia in italy were tested for toxins by mouse bioassay, the microtox system, and gc-ms and hplc chromatography. anatoxin-a was identified by gc-ms after derivatization with pentafluorobenzyl bromide. hepatotoxins were also present and are perhaps related to the microcystins present in other species of anabaena.	1994	8016858
anabaena sp. strain pcc 7120 ntca gene required for growth on nitrate and heterocyst development.	the anabaena sp. strain pcc 7120 ntca (bifa) gene encodes a sequence-specific dna-binding protein, ntca (bifa, vf1) that interacts with the upstream region of several genes, including glna, xisa, rbcl, and nifh. we have constructed a ntca null mutant by interrupting the gene with an omega spr-smr cassette. the ntca mutant was not able to grow with nitrate or atmospheric dinitrogen as the sole nitrogen source but could be grown on medium containing ammonium. the ntca mutant was unable to form het ...	1994	7913926
cloning and nucleotide sequence of the gene encoding dinitrogenase reductase (nifh) from the cyanobacterium nostoc 6720.	the nucleotide sequence of the 3' end of the nifu coding sequence, the complete coding sequence of nifh and a substantial part of the 5' end of nifd coding sequence from nostoc 6720 is presented. the coding sequences are highly conserved with those of anabaena 7120 and anabaena sp. l31. however the intergenic region between nifu and nifh contains two segments of short tandemly repetitive repeat sequences (strrs) that differ from the strr that is common to both anabaena7120 and anabaenasp. l31. v ...	1994	7918657
analysis of expression of the argc and argd genes in the cyanobacterium anabaena sp. strain pcc 7120.	a cloned dna fragment from anabaena sp. strain pcc 7120 that complements an arginine auxotrophic mutant from the same organism was found to include an open reading frame encoding a 427-residue polypeptide that is homologous to n-acetylornithine aminotransferase from bacillus subtilis, escherichia coli, and saccharomyces cerevisiae. the gene encoding n-acetylornithine aminotransferase in bacteria has been named argd. the expression of anabaena sp. strain pcc 7120 argd, as well as of argc, was ana ...	1994	7929012
structure-function relationships of cyanobacterial adp-glucose pyrophosphorylase. site-directed mutagenesis and chemical modification of the activator-binding sites of adp-glucose pyrophosphorylase from anabaena pcc 7120.	chemical modification studies of spinach leaf adp-glucose pyrophosphorylase with pyridoxal-p have shown that a highly conserved lysyl residue near the c terminus might be involved in the binding of 3-p-glycerate, the allosteric activator. site-directed mutagenesis of the corresponding residue (lys419) of the anabaena enzyme was performed to determine the role of this conserved residue. replacing lys419 with either arginine, alanine, glutamine, or glutamic acid produced mutant enzymes with appare ...	1994	7929064
delta 9 acyl-lipid desaturases of cyanobacteria. molecular cloning and substrate specificities in terms of fatty acids, sn-positions, and polar head groups.	in cyanobacteria, the biosynthesis of unsaturated fatty acids is initiated by delta 9 acyl-lipid desaturase which introduces the first double bond at the delta 9 position of a saturated fatty acid that has been esterified to a glycerolipid. we have cloned genes, designated desc, for delta 9 acyl-lipid desaturases from two cyanobacteria, namely anabaena variabilis and synechocystis sp. pcc 6803. these desaturases, when expressed in escherichia coli, desaturated stearic acid to yield oleic acid at ...	1994	7929259
two mutations that block heterocyst differentiation have different effects on akinete differentiation in nostoc ellipsosporum.	evident differentiation of vegetative cells into heterocysts in anabaena sp. strain pcc 7120 is prevented by insertions in genes hetr and hetp. nostoc ellipsosporum possesses single copies of genes that hybridize with hetr and hetp. in mutant ne2 of n. ellipsosporum, in which hetr is interrupted by an insert, and in a double recombinant of wild-type n. ellipsosporum with a plasmid that bears an interrupted copy of hetr, neither heterocysts nor akinetes are formed. when an intact copy of hetr fro ...	1994	7934891
esr and endor characterization of flavodoxin from anabaena sp. pcc 7119.		1994	7821623
protein engineering for the elucidation of the mechanism of electron transfer in redox proteins.		1994	7821688
catalysis of rna cleavage by a ribozyme derived from the group i intron of anabaena pre-trna(leu).	in the cyanobacterium anabaena pcc7120, the precursor to trna(leu) contains a 249-nucleotide group i intron that undergoes efficient self-splicing in vitro. by deleting the 5' and 3' splice sites, this intron has now been converted to an rna enzyme that uses a guanosine nucleophile to cleave substrate rnas (s) with multiple turnover. this anabaena ribozyme has a second-order rate constant for rna cleavage (kcat/km)s that is 250-500-fold smaller than that of the tetrahymena ribozyme, and a multip ...	1994	7527660
requirement of the regulatory protein ntca for the expression of nitrogen assimilation and heterocyst development genes in the cyanobacterium anabaena sp. pcc 7120.	the cyanobacterial ntca gene encodes a dna-binding protein that belongs to the crp family of bacterial transcriptional regulators. in this work, we describe the isolation of an ntca insertional mutant of the dinitrogen-fixing, heterocyst-forming cyanobacterium anabaena sp. pcc 7120. the anabaena ntca mutant was able to use ammonium as a source of nitrogen for growth, but was unable to assimilate atmospheric nitrogen (dinitrogen) or nitrate. nitrogenase and enzymes of the nitrate reduction system ...	1994	7534371
x-ray microanalysis with the environmental scanning electron microscope: interpretation of data obtained under different atmospheric conditions.	x-ray microanalysis of non-biological and biological specimens was carried out in an environmental scanning electron microscope (esem) over a range of atmospheric conditions. introduction of water vapour into the specimen chamber lead to direct x-ray contribution from oxygen atoms, an increase in extraneous background (causing reduced p/b ratios of other elements), x-ray absorption (also reducing p/b ratios) and broadening (skirting) of the electron beam. similar results were obtained after intr ...	1994	7638489
protein hu from the cyanobacterium anabaena.	protein hu was purified from the cyanobacterium anabaena 7120. its complete amino acid sequence was determined by automated edman degradation of the whole protein and of cnbr and chymotryptic peptides. the active dna-binding protein is a homodimer of 94-amino acid subunits. approximately half of the residues are identical to those of the two subunits of hu protein from e. coli. the protein binds to both supercoiled and relaxed double-stranded dna, cooperatively. the contour lengths of circular d ...	1994	7748931
representation of the secondary and tertiary structure of group i introns.	group i introns, which are widespread in nature, carry out rna self-splicing. the secondary structure common to these introns was for the most part established a decade ago. information about their higher order structure has been derived from a range of experimental approaches, comparative sequence analysis, and molecular modelling. this information now provides the basis for a new two-dimensional structural diagram that more accurately represents the domain organization and orientation of helic ...	1994	7545072
nadp(+)-isocitrate dehydrogenase from the cyanobacterium anabaena sp. strain pcc 7120: purification and characterization of the enzyme and cloning, sequencing, and disruption of the icd gene.	nadp(+)-isocitrate dehydrogenase (nadp(+)-idh) from the dinitrogen-fixing filamentous cyanobacterium anabaena sp. strain pcc 7120 was purified to homogeneity. the native enzyme is composed of two identical subunits (m(r), 57,000) and cross-reacts with antibodies obtained against the previously purified nadp(+)-idh from the unicellular cyanobacterium synechocystis sp. strain pcc 6803. anabaena nadp(+)-idh resembles in its physicochemical and kinetic parameters the typical dimeric idhs from prokar ...	1994	8169222
immunological and functional localization of both f-type and p-type atpases in cyanobacterial plasma membranes.	plasma and thylakoid membranes were prepared and purified from cyanobacteria anacystis nidulans (synechococcus pcc6301), synechocystis pcc6803, and anabaena pcc7120 grown photoautotrophically in axenic batch cultures and harvested either during early exponential growth (< 1 microliter packed cell mass/ml medium; light-saturated cells) or during linear growth (2-3 microliters packed cell mass/ml medium; light-limited cells). atpase activities of methanol-activated membranes were determined by mea ...	1994	8179623
a cold-regulated cyanobacterial gene cluster encodes rna-binding protein and ribosomal protein s21.	a cold-regulated gene cluster, rbpa-rpsu, was isolated by differential screening in the cyanobacterium anabaena variabilis m3. the two genes were co-transcribed as a 900 nt transcript. the level of this transcript was 5-10 times higher in cells grown at 22 degrees c than in those grown at 38 degrees c. the rbpa protein, which was homologous to plant glycine-rich proteins, exhibited a strong affinity to rna from this cyanobacterium.	1994	8193307
identification of conserved domains in the delta 12 desaturases of cyanobacteria.	cyanobacterial genes for enzymes that desaturate fatty acids at the delta 12 position, designated desa, were isolated from synechocystis pcc6714, synechococcus pcc7002 and anabaena variabilis by cross-hybridization with a dna probe derived from the desa gene of synechocystis pcc6803. the genes of synechocystis pcc6714, synechococcus pcc7002 and a. variabilis encode proteins of 349, 347 and 350 amino acid residues, respectively. the transformation of synechococcus pcc7942 with the desa genes from ...	1994	8155883
analysis of a het- mutation in anabaena sp. strain pcc 7120 implicates a secondary metabolite in the regulation of heterocyst spacing.	transposon-generated mutant n10 of anabaena sp. strain pcc 7120 has a het- phenotype (a. ernst, t. black, y. cai, j.-m. panoff, d. n. tiwari, and c. p. wolk, j. bacteriol. 174:6025-6032, 1992). reconstruction of the transposon mutation reproduced a het- phenotype, but reconstructions with other insertions at the position of the transposon produced strains that form multiple contiguous heterocysts. sequence analysis around the site of insertion of the transposon showed that the insertion lies wit ...	1994	8157596
evidence that sigma factors are components of chloroplast rna polymerase.	plastid genes are transcribed by dna-dependent rna polymerase(s), which have been incompletely characterized and have been examined in a limited number of species. plastid genomes contain rpoa, rpob, rpoc1, and rpoc2 coding for alpha, beta, beta', and beta" rna polymerase subunits that are homologous to the alpha, beta, and beta' subunits that constitute the core moiety of rna polymerase in bacteria. however, genes with homology to sigma subunits in bacteria have not been found in plastid genome ...	1994	8159791
detection and characterization of cyanobacterial nifh genes.	the dna sequence of a 359-bp fragment of nifh was determined for the heterocystous strains anabaena sp. strain ca (atcc 33047), nostoc muscorum utex 1933, a nostoc sp., gloeothece sp. strain atcc 27152, lyngbya lagerheimii utex 1930, and plectonema boryanum iu 594. results confirmed that the dna sequence of the 359-bp segment is sufficiently variable to distinguish cyanobacterial nifh genes from other eubacterial and arachaeobacterial nifh genes, as well as to distinguish heterocystous from nonh ...	1994	8161180
delay of cell differentiation in anabaena aequalis caused by uv-b radiation and the role of photoreactivation and excision repair.	the effect of ultraviolet light on cell differentiation was studied in the cyanobacterium anabaena aequalis. exposure of cells to uv-b wavelengths (280-320 nm) significantly delayed the differentiation of vegetative cells into heterocysts and akinetes at doses up to 56 kj m-2. heterocyst differentiation was essentially stopped at all exposure levels when photoreactivation was prevented, even when excision repair was available to the cells. photoreactivated samples produced heterocysts at doses t ...	1994	8165241
nucleotide sequences of the psaa and the psab genes encoding the reaction center proteins of photosystem i in anabaena variabilis atcc 29413.	we have determined the nucleotide sequence of the psaab gene cluster from the filamentous cyanobacterium anabaena variabilis atcc 29413. these genes encode the photosystem i reaction center proteins, which are highly homologous to similar proteins in other cyanobacteria and higher plants.	1994	8167140
characterization of the genome region encoding an fdxh-type ferredoxin and a new 2[4fe-4s] ferredoxin from the nonheterocystous, nitrogen-fixing cyanobacterium plectonema boryanum pcc 73110.	a genomic dna region with four consecutive open reading frames, including an fdxh-type gene, has been sequenced and initially characterized for the nonheterocystous nitrogen-fixing cyanobacterium plectonema boryanum pcc 73110. the fdxh gene encodes a [2fe-2s]-type ferredoxin, 98 amino acids in length, with a deduced molecular mass of 10.9 kda. conserved residues include two characteristic lysines at positions 10 and 11, shown recently to be important for interaction with nitrogenase reductase (s ...	1994	8106314
transfer of a genetic marker from a megaplasmid of anabaena sp. strain pcc 7120 to a megaplasmid of a different anabaena strain.	the 410-kb alpha megaplasmid of the heterocyst-forming cyanobacterium anabaena sp. strain pcc 7120 was found to bear the nuca gene that encodes a sugar-nonspecific nuclease. that gene was mutated by insertion of a cassette that confers resistance to neomycin. the resulting strain, amp2, was mated with a streptomycin-resistant derivative of anabaena sp. strain pcc 7118, a strain that does not form heterocysts. cells resistant to both neomycin and streptomycin that were derived from such matings w ...	1994	8106321
photosystem ii genes isia, psbdi and psbc in anabaena sp. pcc 7120: cloning, sequencing and the transcriptional regulation in iron-stressed and iron-repleted cells.	under conditions of iron deprivation cyanobacteria produce flavodoxin to replace ferredoxin as the terminal electron acceptor of photosynthesis. in unicellular cyanobacteria, the gene for flavodoxin is the second open reading frame in a dicistronic operon whose transcription is tightly regulated by iron. the first gene, isia, produces a protein that is very similar to cp43, a chlorophyll-binding, antenna protein of the photosystem ii reaction center. in the filamentous, heterocystous cyanobacter ...	1994	8111027
a novel carotenoid biosynthesis gene coding for zeta-carotene desaturase: functional expression, sequence and phylogenetic origin.	a dna fragment which has been isolated previously from an anabaena dna expression library was subcloned. the corresponding protein was overexpressed in escherichia coli. the recombinant enzyme was fully active in converting zeta-carotene into lycopene in vitro with neurosporene as an intermediate. a smaller fragment which still contained the active enzyme was sequenced. an open reading frame of 1497 bp was found coding for a protein consisting of 499 amino acids with the calculated molecular wei ...	1994	8111038
two anabaena sp. strain pcc 7120 dna-binding factors interact with vegetative cell- and heterocyst-specific genes.	the dna-binding factor bifa (previously called vf1) binds upstream of the developmentally regulated site-specific recombinase gene xisa in the cyanobacterium anabaena sp. strain pcc 7120. besides binding xisa, bifa also binds the glna, rbcl, and nifh promoter regions. dnase i footprint analysis of bifa binding to glna showed a protected region -125 to -148 bp upstream of the translation start site. the binding site is between the major glna transcription start site used in vegetative cells (rnai ...	1994	8113160