Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0031511 (pheochromocytoma)
 14,622 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A stable DNA/protein complex having an apparent molecular mass of approximately 150 kDa was purified from nitrate-limited cultures of the cyanobacterium Synechococcus sp. strain PCC 7942. Amino-terminal peptide sequencing indicated that the polypeptide was structurally similar to the Dps protein of Escherichia coli; Dps is also known as the product of the starvation- and stationary-phase-inducible gene, pexB. The 150-kDa complex dissociated into a 22-kDa protein monomer after boiling in 2% SDS. The 150-kDa complex preparation had approximately a 10% nucleic acid content and upon dissociation released DNA fragments that were sensitive to S1 nuclease digestion. Immunoblot data indicated that the complex accumulates during stationary phase and during nitrogen, sulfur, and phosphorus limitation. DNA-binding assays indicated that the protein nonspecifically binds both linear and supercoiled DNA. Circular dichroism spectroscopy revealed that the Synechococcus sp. Dps-like protein contains extensive regions of alpha-helical secondary structure. We propose that the 150-kDa complex represents a hexameric aggregate of the Dps-like protein complexed with single-stranded DNA and serves to bind a portion of the chromosomal DNA under nutrient-limited conditions.
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PMID:Purification and characterization of a Synechococcus sp. strain PCC 7942 polypeptide structurally similar to the stress-induced Dps/PexB protein of Escherichia coli. 779 1

The gene encoding the cytochrome b6 subunit (petB) of the cytochrome b6f complex has been isolated, cloned and sequenced by nonradioactive methods from genomic DNA of the unicellular cyanobacterium Synechocystis sp. PCC 6803. The coding region consists of 666 nucleotides, coding for a polypeptide with a molecular mass of 25.02 kDa. In contrast to higher plant petB sequences an aminoterminal extension of seven amino acids occurs. Aminoterminal sequencing of the isolated protein excludes--different from higher plants--the existence of an intron after the first amino acids but indicate the posttranslational removal of three amino acids from the amino terminus. The aminoterminal extension--found only in non-nitrogen-fixing, unicellular cyanobacteria--shows a high degree of homology between different species.
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PMID:Nucleotide sequence of the petB gene encoding cytochrome b6 from the mesophilic cyanobacterium Synechocystis PCC 6803: implications for evolution and function. 780 59

Programmed DNA rearrangements that occur during cellular differentiation are uncommon and have been described in only two prokaryotic organisms. Here, we identify the developmentally regulated rearrangement of a hydrogenase gene in heterocysts of the cyanobacterium Anabaena sp. strain PCC 7120. Heterocysts are terminally differentiated cells specialized for nitrogen fixation. Late during heterocyst differentiation, a 10.5-kb DNA element is excised from within the hupL gene by site-specific recombination between 16-bp direct repeats that flank the element. The predicted HupL polypeptide is homologous to the large subunit of [NiFe] uptake hydrogenases. hupL is expressed similarly to the nitrogen-fixation genes; hupL message was detected only during the late stages of heterocyst development. An open reading frame, named xisC, identified near one end of the hupL DNA element is presumed to encode the element's site-specific recombinase. The predicted XisC polypeptide is homologous with the Anabaena sp. strain PCC 7120 site-specific recombinase XisA. Neither XisC nor XisA shows sequence similarity to other proteins, suggesting that they represent a different class of site-specific recombinase.
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PMID:Programmed DNA rearrangement of a cyanobacterial hupL gene in heterocysts. 784 53

Nostoc sp. strain ATCC 29133 (PCC 73102; Nostoc 29133) is a symbiotically-competent, facultatively heterotrophic, diazotrophic cyanobacterium with the capacity to differentiate specialized cells such as heterocysts, akinetes and hormogonial filaments. We have optimized several methods for physiological and molecular genetic analysis of Nostoc 29133. By use of a Tn5 derivative, Tn5-1063 (Km(r)Bm(r)Sm(r)), delivered by conjugation from Escherichia coli, antibiotic-resistant mutants of Nostoc 29133 were generated at a frequency of approximately 1 x 10(-6), 0.4% of which expressed a nitrogen fixation (heterocyst) defective phenotype. Mutant strain UCD 328 was isolated after co-culture of 86 Nostoc 29133::Tn5-1063 clones with the symbiotic plant partner, Anthoceros punctatus; strain UCD 328 expressed a symbiotic phenotype of increased frequency of hormogonia-dependent infection. The transposon and flanking genomic DNA was recovered from strain UCD 328, the mutation and phenotype reconstructed by homologous recombination in Nostoc 29133, and the transposition site identified from a Nostoc 29133 genomic library. Transposon mutagenesis has thus provided the means for isolation and identification of developmental and symbiotic-specific genes of Nostoc 29133.
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PMID:Transposon mutagenesis of Nostoc sp. strain ATCC 29133, a filamentous cyanobacterium with multiple cellular differentiation alternatives. 788 44

Strain 129 is a fragmentation mutant of the filamentous cyanobacterium Anabaena sp. strain PCC 7120. Growing with fixed nitrogen, this mutant forms filaments that are much shorter than wild-type filaments. Following starvation for fixed nitrogen, strain 129 becomes nearly unicellular and forms few heterocysts, although electron microscopy suggests that proheterocysts form while fragmentation occurs. Starvation for sulfate, phosphate, iron, and calcium does not cause this fragmentation. The affected gene in strain 129, fraC, was cloned by complementation and characterized. It encodes a unique 179-amino-acid protein rich in phenylalanine. Insertional inactivation of the chromosomal copy of fraC results in a phenotype identical to that of strain 129, while complementation using a truncated version of FraC results in only partial complementation of the original mutant. Heterocysts could be induced to form in N-replete cultures of strain 129, as in wild-type cells, by supplying extra copies of the hetR gene on a plasmid. Thus, FraC is required for the integrity of cell junctions in general but is apparently not directly involved in normal differentiation and nitrogen fixation.
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PMID:A short-filament mutant of Anabaena sp. strain PCC 7120 that fragments in nitrogen-deficient medium. 788 9

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 7942 transcription regulator, NtcA, were found upstream of the transcription initiation site.
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PMID:Expression of glnA in the cyanobacterium Synechococcus sp. strain PCC 7942 is initiated from a single nif-like promoter under various nitrogen conditions. 790 50

A new glutamine synthetase gene, glnN, which encodes a polypeptide of 724 amino acid residues (M(r), 79,416), has been identified in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803; this is the second gene that encodes a glutamine synthetase (GS) in this cyanobacterium. The functionality of this gene was evidenced by its ability to complement an Escherichia coli glnA mutant and to support Synechocystis growth in a strain whose glnA gene was inactivated by insertional mutagenesis. In this mutant (strain SJCR3), as well as in the wild-type strain, the second GS activity was subject to regulation by the nitrogen source, being strongly enhanced in nitrogen-free medium. Transcriptional fusion of a chloramphenicol acetyltransferase (cat) gene with the 5'-upstream region of glnN suggested that synthesis of the second Synechocystis GS is regulated at the transcriptional level. Furthermore, the level of glnN mRNA, a transcript of about 2,300 bases, was found to be strongly increased in nitrogen-free medium. The glnN product is similar to the GS subunits of Bacteroides fragilis and Butyrivibrio fibrisolvens, two obligate anaerobic bacteria whose GSs are markedly different from other prokaryotic and eukaryotic GSs. However, significant similarity is evident in the five regions which are homologous in all of the GSs so far described. The new GS gene was also found in other cyanobacteria but not in N2-fixing filamentous species.
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PMID:A new type of glutamine synthetase in cyanobacteria: the protein encoded by the glnN gene supports nitrogen assimilation in Synechocystis sp. strain PCC 6803. 790 87

A monospecific anti-(glutamine synthetase) antibody raised against glutamine synthetase of the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 immunoreacted with glutamine synthetase from the N2-fixing heterotrophic bacterium Azotobacter chroococcum. In Western-blotting experiments this antibody recognized a single protein of a molecular mass of 59 kDa corresponding to glutamine synthetase subunit. This protein was in vivo-labelled in response to addition of ammonium, both [3H]adenine and H(3)32PO4 preincubation of the cells being equally effective. Nevertheless, the amount of glutamine synthetase present in A. chroococcum was independent of the available nitrogen source. Modified, inactive glutamine synthetase was re-activated by treatment with snake-venom phosphodiesterase but not by alkaline phosphatase. L-Methionine-DL-sulphoximine, an inhibitor of glutamine synthetase, prevented the enzyme from being covalently modified. We conclude that, in A. chroococcum, glutamine synthetase is adenylylated in response to ammonium and that for the modification to take place ammonium must be metabolized.
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PMID:In vivo modification of Azotobacter chroococcum glutamine synthetase. 790 89

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 heterocysts and did not rearrange the nifD or fdxN elements after induction on a medium lacking combined nitrogen. Northern (RNA) analysis of ntcA in the wild-type strain during nitrogen stepdown showed a peak of ntcA message at an early stage (12 h) of heterocyst induction. Complementation of the ntcA mutant with a DNA fragment containing the ntcA gene and 251 bp of upstream sequence on a shuttle vector restored a wild-type phenotype; however, a similar construction containing 87 bp of upstream sequence only partially restored the phenotype. Northern analysis of RNA samples isolated from ammonium-grown cultures of the ntcA mutant showed reduced amounts of glnA message and the absence of a 1.7-kb transcript. In the wild type, the 1.7-kb transcript represents the majority of glnA transcripts after nitrogen stepdown. The ntcA mutant showed a normal pattern of rbcLS messages under these growth conditions.
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PMID:Anabaena sp. strain PCC 7120 ntcA gene required for growth on nitrate and heterocyst development. 791 26

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 rbc transcripts accumulated in the light and diminished in the dark; light-dependent expression of these genes was not affected by the nitrogen source and the concentration of exogenous CO2 supplied to the cells. When grown on fructose, rca- and rbc-specific transcripts accumulated in A. variabilis regardless of whether the cells were illuminated. Transcript levels, however, were much lower in dark-grown heterotrophic cultures than in photoheterotrophic cultures. In photoheterotrophic cultures, the expression of the rca and rbc genes was similar to that in cultures grown with CO2 as the sole source of carbon. Although the rbcL-rbcS and rca genes are linked and are in the same transcriptional orientation in Anabaena strains, hybridization of rbc and rca to distinct transcripts suggested that these genes are not cotranscribed, consistent with the results of primer extension and secondary structure analysis of the nucleotide sequence. Transcription from ORF1 and ORF2 was not detected under the conditions examined, and the function of these putative genes remains unknown.
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PMID:Transcription control of ribulose bisphosphate carboxylase/oxygenase activase and adjacent genes in Anabaena species. 796 23


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