Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several species of fish from the genus Poeciliopsis differ dramatically in their response to the carcinogen N-nitrosodiethylamine (NDEA). The differential induction of tumors among genotypes exposed to NDEA may, in part, result from differences in liver cytochrome P450pj activity (the piscine equivalent of mammalian P450j). Evidence for the existence of cytochrome P450pj activity and mRNA expression has been found in several Poeciliopsis genotypes (species and strains). Biochemical evidence suggests that a microsomal cytochrome P450 enzyme catalyzes the metabolism of NDEA to acetaldehyde and other intermediates in Poeciliopsis. This reaction was inhibited by carbon monoxide, and required molecular oxygen and reducing equivalents (NADPH). Differences were found in maximal activity as well as temperature optima among genotypes. Poeciliopsis, a livebearing fish from desert streams of northwestern Mexico, appears to have thermal optima for cytochrome P450pj activity between 25 and 30 degrees C depending on the genotype. Western blot analysis (using anti-rat P450IIE1 antibodies) detected a 55-60 kd band in microsomes isolated from rat and Poeciliopsis. Using a 49mer probe specific for rat cytochrome P450j, Northern blots revealed a 3.3 kb mRNA from livers of a Poeciliopsis genotype and rat, but none in muscle mRNA from either organism. S1 nuclease protection assays, using the same probe, revealed that a mRNA fragment protected by the probe against digestion was induced on exposure of the whole organism to ethanol (via uptake from the aquatic environment). The assays also demonstrated that ethanol treatments both induced and suppressed this mRNA, depending on concentration and exposure time.
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PMID:Nitrosodiethylamine metabolism in the viviparous fish Poeciliopsis: evidence for the existence of liver P450pj activity and expression. 201 28

Autotrophic CO2 fixation via the Calvin carbon reduction cycle in Alcaligenes eutrophus H16 is genetically determined by two highly homologous cbb operons, one of which is located on the chromosome and the other on megaplasmid pHG1 of the organism. An activator gene, cbbR, lies in divergent orientation only 167 bp upstream of the chromosomal operon and controls the expression of both cbb operons. The two 5'-terminal genes of the operons, cbbLS, coding for ribulose-1,5-bisphosphate carboxylase/oxygenase, were sequenced. Mapping of the 5' termini of the 2.1-kb cbbLS transcripts by primer extension and by nuclease S1 treatment revealed a single transcriptional start point at the same relative position for the chromosomal and plasmid-borne cbb operons. The derived cbb operon promoter showed similarity to sigma 70-dependent promoters of Escherichia coli. For the 1.4-kb transcripts of cbbR, the transcriptional start points were different in autotrophic and heterotrophic cells. The two corresponding cbbR promoters overlapped the cbb operon promoter and also displayed similarities to sigma 70-dependent promoters. The deficient cbbR gene located on pHG1 was transcribed as well. A newly constructed double operon fusion vector was used to determine the activities of the cbb promoters. Fusions with fragments carrying the cbb intergenic control regions demonstrated that the cbb operon promoters were strongly regulated in response to autotrophic versus heterotrophic growth conditions. In contrast, the cbbR promoters displayed low constitutive activities. The data suggest that the chromosomal and plasmid-borne cbb promoters of A. eutrophus H16 are functionally equivalent despite minor structural differences.
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PMID:Characterization of the duplicate ribulose-1,5-bisphosphate carboxylase genes and cbb promoters of Alcaligenes eutrophus. 754 77

Transcription of the antiphagocytic M protein in the group A streptococcus (Streptococcus pyogenes) is environmentally regulated in response to CO2 and requires Mry, a trans-acting positive regulatory protein. We have examined the role of Mry in environmental regulation by analysing the factors that regulate expression of the gene that encodes Mry (mry). By employing a strategy that utilizes integrational plasmids, it was found that expression of mry requires the participation of DNA sequences that extend 473 base pairs upstream of the Mry coding region. Transcription of mry, as analysed in S1 nuclease protection assays, is initiated from two separate promoters located within this extended regulatory region. Construction and analysis of transcriptional fusions between the mry promoters and a promoterless chloramphenicol acetyltransferase gene demonstrated that mry is autoregulated and environmentally regulated in response to the level of CO2. These data suggest a model for the regulation of virulence in S. pyogenes where positive transcriptional control of mry in response to environmental stimuli regulates the expression of the M protein.
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PMID:Positive transcriptional control of mry regulates virulence in the group A streptococcus. 848 19

Phenotypic and genetic traits of porcine intestinal spirochete strain P43/6/78T (= ATCC 51139T) (T = type strain), which is pathogenic and weakly beta-hemolytic, were determined in order to confirm the taxonomic position of this organism and its relationships to previously described species of intestinal spirochetes. In BHIS broth, P43/6/78T cells had a doubling time of 1 to 2 h and grew to a maximum cell density of 2 x 10(9) cells per ml at 37 to 42 degrees C. They hydrolyzed hippurate, utilized D-glucose, D-fructose, sucrose, D-trehalose, D-galactose, D-mannose, maltose, N-acetyl-D-glucosamine, D-glucosamine, pyruvate, L-fucose, D-cellobiose, and D-ribose as growth substrates, and produced acetate, butyrate, ethanol, H2, and CO2 as metabolic products. They consumed substrate amounts of oxygen and had a G+C content (24.6 mol%) similar to that of Serpulina hyodysenteriae B78T (25.9 mol%). Phenotypic traits that could be used to distinguish strain P43/6/78T from S. hyodysenteriae and Serpulina innocens included its ultrastructural appearance (each strain P43/6/78T cell had 8 or 10 periplasmic flagella, with 4 or 5 flagella inserted at each end, and the cells were thinner and shorter and had more pointed ends than S. hyodysenteriae and S. innocens cells), its faster growth rate in liquid media, its hydrolysis of hippurate, its lack of beta-glucosidase activity, and its metabolism of D-ribose. DNA-DNA relative reassociation experiments in which the S1 nuclease method was used revealed that P43/6/78T was related to, but was genetically distinct from, both S. hyodysenteriae B78T (level of sequence homology, 25 to 32%) and S. innocens B256T (level of sequence homology, 24 to 25%). These and previous results indicate that intestinal spirochete strain P43/6/78T represents a distinct Serpulina species. Therefore, we propose that strain P43/6/78 should be designated as the type strain of a new species, Serpulina pilosicoli.
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PMID:Serpulina pilosicoli sp. nov., the agent of porcine intestinal spirochetosis. 857 97