Disease relevance of Anabaena

• A DNA-binding protein has been isolated from two cyanobacteria (blue-green algae): Anabaena sp and Aphanocapsa sp. It has a molecular weight as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis of about 10,000, is rich in lysine and arginine, and lacks tyrosine, tryptophan, and cysteine [1].
• These altered small subunits were cosynthesized with large subunits (from an expressed Anabaena rbcL gene) in Escherichia coli [2].
• During oxygenic photosynthesis, cytochrome c(6) shuttles electrons between the membrane-bound complexes cytochrome bf and photosystem I. Complex formation between Phormidium laminosum cytochrome f and cytochrome c(6) from both Anabaena sp. PCC 7119 and Synechococcus elongatus has been investigated by nuclear magnetic resonance spectroscopy [3].
• In contrast to the monomeric Anabaena nuclease, the Serratia nuclease is a dimer of two identical subunits [4].
• This is the first report on the detection and purification of ubiquitin from a eubacterium, the cyanobacterium Anabaena variabilis [5].

High impact information on Anabaena

• Nitrogen fixation by the cyanobacterium Anabaena is carried out in heterocysts, specialized, non-dividing cells which differentiate under conditions of ammonia or nitrate deprivation [6].
• Overexpression of a 54-base-pair gene, patS, blocked heterocyst differentiation in Anabaena sp. strain PCC 7120 [7].
• A self-splicing group I intron has been found in the gene for a leucine transfer RNA in two species of Anabaena, a filamentous nitrogen-fixing cyanobacterium [8].
• Genome rearrangement and nitrogen fixation in Anabaena blocked by inactivation of xisA gene [9].
• Anabaena xisF gene encodes a developmentally regulated site-specific recombinase [10].

Chemical compound and disease context of Anabaena

• In RNA isolated from the endosymbiont there is a 10-fold reduction of GS transcript levels, a greater than 5-fold increase in 32-kd transcript levels and a greater than 5-fold decrease in RuBP carboxylase transcript levels, compared with levels in the free-living Anabaena azollae [11].
• Cocrystal structures of Anabaena HU bound to DNA (1P71, 1P78, 1P51) reveal that while underlying proline intercalation and asymmetric charge neutralization mechanisms of DNA bending are similar for IHF and HU, HU stabilizes different DNA bend angles ( approximately 105-140 degrees ) [12].
• The coding sequence for Anabaena 7120 glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.1] are shown to be contained within a 7.5-kilobase-pair (kbp) HindIII fragment that has been cloned by plaque hybridization [13].
• The rbcL-rbcS transcript is equally abundant in Anabaena azollae grown in the light or on fructose in the dark [14].
• Sucrose biosynthesis in a prokaryotic organism: Presence of two sucrose-phosphate synthases in Anabaena with remarkable differences compared with the plant enzymes [15].

Biological context of Anabaena

• The symbiont rbcL gene shared the highest degree of nucleotide sequence identity with the cyanobacterium Anabaena (69%) while the rbcS nucleotide sequence shared 61% identity with that of the green alga Chlamydomonas reinhardtii [16].
• To explore the role of individual residues in the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39), small subunits with single amino acid substitutions in three regions of relative sequence conservation were produced by directed mutagenesis of the rbcS gene from Anabaena 7120 [2].
• The patA mutation suppresses the multiheterocyst phenotype produced by extra copies of the wild-type hetR gene described previously, suggesting that PatA and HetR are components of the same environment-sensing regulatory circuit in Anabaena [17].
• The tandem GAF domains from the cyanobacterium Anabaena PCC7120 cyaB2 adenylyl cyclase form an antiparallel dimer with cAMP bound to all four binding sites. cAMP binding causes highly cooperative allosteric enzyme activation (>500-fold; EC(50) = 1 microM; Hill coefficient >2.0) [18].
• Nitrogen-regulated genes for the metabolism of cyanophycin, a bacterial nitrogen reserve polymer: expression and mutational analysis of two cyanophycin synthetase and cyanophycinase gene clusters in heterocyst-forming cyanobacterium Anabaena sp. PCC 7120 [19].

Anatomical context of Anabaena

• Thioredoxin from Anabaena sp. has been purified 800-fold with an assay based on the reduction of insulin disulfides by NADPH and the heterologous calf thymus thioredoxin reductase [20].
• Experiments with sodium azide support the earlier report that two different photoreceptor systems participate in the absorption of the phototactically active light in Anabaena variabilis [21].
• Cultured cells of Anabaena flos-aquae strain CYA 83/1, isolated from Lake Edlandsvatn, Norway, produced two microcystin mono-methyl ester derivatives (1 and 2) at the D-Glu unit in addition to microcystin-LR (3), [D-Asp3]microcystin-LR (4), microcystin-RR (5), and [D-Asp3]microcystin-RR (6) [22].
• Cytochrome b/c complexes with polyprenyl quinol:cytochrome c oxidoreductase activity from Anabaena variabilis and Rhodopseudomonas sphaeroides GA: comparison of preparations from chloroplasts and mitochondria [23].

Gene context of Anabaena

• In the filamentous cyanobacterium Anabaena, the gene for the small subunit (rbcS) of ribulose-1,5-bisphosphate carboxylase is linked to and transcribed together with the gene encoding the large subunit (rbcL) of the same enzyme [14].
• Comparison of the nifB 5'-flanking sequence with the nifH 5'-flanking sequence did not reveal any consensus base pairs that would define a nif promoter for Anabaena [24].
• An Anabaena nucA insertional mutant was generated which failed to produce the 29 kDa nuclease [25].
• Summary In the filamentous cyanobacterium Anabaena sp. PCC 7120 patS and hetN suppress the differentiation of vegetative cells into nitrogen-fixing heterocysts to establish and maintain a pattern of single heterocysts separated by approximately 10 undifferentiated vegetative cells [26].
• An Anabaena ntcB mutant was able to use ammonium and dinitrogen as sources of nitrogen for growth but was unable to assimilate nitrate [27].

Analytical, diagnostic and therapeutic context of Anabaena

• Site-directed mutagenesis of cytochrome c(6) from Anabaena species PCC 7119. Identification of surface residues of the hemeprotein involved in photosystem I reduction [28].
• Comparative sequence analysis has placed this intron and the Anabaena pre-tRNA(Leu) intron into the same subgroup, IC3; we now compare their activity and stability [29].
• Crystallization and structure determination to 2.5-A resolution of the oxidized [2Fe-2S] ferredoxin isolated from Anabaena 7120 [30].
• FTIR spectroscopy of the all-trans form of Anabaena sensory rhodopsin at 77 K: hydrogen bond of a water between the Schiff base and Asp75 [31].
• Protein engineering on Arg100 and Arg264 from Anabaena PCC 7119 FNR has been carried out to investigate their roles in complex formation and electron transfer to NADP+ and to ferredoxin/flavodoxin [32].

References