Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Schizosaccharomyces pombe temperature-sensitive mutant snm1 maintains reduced steady-state quantities of the spliceosomal small nuclear RNAs (snRNAs) and the RNA subunit of the tRNA processing enzyme RNase P. We report here the isolation of the pac1+ gene as a multi-copy suppressor of snm1. The pac1+ gene was previously identified as a suppressor of the ran1 mutant and by its ability to cause sterility when overexpressed. The pac1+ gene encodes a double-strand-specific ribonuclease that is similar to RNase III, an RNA processing and turnover enzyme in Escherichia coli. To investigate the essential structural features of the Pac1 RNase, we altered the pac1+ gene by deletion and point mutation and tested the mutant constructs for their ability to complement the snm1 and ran1 mutants and to cause sterility. These experiments identified four essential amino acids in the Pac1 sequence: glycine 178, glutamic acid 251, and valines 346 and 347. These amino acids are conserved in all RNase III-like proteins. The glycine and glutamic acid residues were previously identified as essential for E. coli RNase III activity. The valines are conserved in an element found in a family of double-stranded RNA binding proteins. Our results support the hypothesis that the Pac1 RNase is an RNase III homolog and suggest a role for the Pac1 RNase in snRNA metabolism.
Mol Gen Genet 1995 Jun 25
PMID:Rescue of the fission yeast snRNA synthesis mutant snm1 by overexpression of the double-strand-specific Pac1 ribonuclease. 761 61

Constitutive stable DNA replication (cSDR), which uniquely occurs in Escherichia coli rnhA mutants deficient in ribonuclease HI activity, requires RecA function. The recA428 mutation, which inactivates the recombinase activity but imparts a constitutive coprotease activity, blocks cSDR in rnhA mutants. The result indicates that the recombinase activity of RecA, which promotes homologous pairing and strand exchange, is essential for cSDR. Despite the requirement for RecA recombinase activity, mutations in recB, recD, recJ, ruvA and ruvC neither inhibit nor stimulate cSDR. It was proposed that the property of RecA essential for homologous pairing and strand exchange is uniquely required for initiation of cSDR in rnhA mutants without involving the homologous recombination process. The possibility that RecA protein is necessary to counteract the action of Tus protein, a contra-helicase which stalls replication forks in the ter region of the chromosome, was ruled out because introduction of the tus::kan mutation, which inactivates Tus protein, did not alleviate the RecA requirement for cSDR.
Mol Gen Genet 1994 Sep 01
PMID:RecA, Tus protein and constitutive stable DNA replication in Escherichia coli rnhA mutants. 807 83

We have identified a family of repetitive sequences in the genome of Nicotiana alata named Tna1 (Transposon of N. alata). The first element we characterised was a genomic clone for the N. alata s6-ribonuclease (S6-RNase), a gene required for self-incompatibility in this species. The DNA sequence of this element resembles the integrase domain of retrotransposons of the gypsy class and is most similar to a retrotransposon from Lilium henryi. A transcript present in N.alata styles (self-incompatibility genotype S6S6) hybridized to Tna1 and accumulated in the style following either pollination or touching. This transcript was cloned from a cDNA library and was encoded by second, partial Tna1 elements. Neither the transcribed sequence nor the original Tna1 element contain an open reading frame or is likely to be able to transpose. The second element was mapped using a population of N.alata plants segregating for alleles of the self-incompatibility locus and is closely linked to the S6-allele. The Tna1 element is present in a number of Nicotiana species and appears to have been active at least twice during the evolution of this genus.
Mol Gen Genet 1996 Feb 05
PMID:A retrotransposon-like sequence linked to the S-locus of Nicotiana alata is expressed in styles in response to touch. 862 17

The chloroplast-derived sequence trnS-rps4/ 3'trnL-trnF-ndhJ-ndhK (4066 bases in length) is present in a region that starts 355 bases upstream of the gene for subunit 9 of NADH dehydrogenase (nad9) in the mitochondrial genome of rice. Northern blot hybridization revealed that three large transcripts of 3.05, 1.62 and 1.05 kb hybridized to strand-specific probes for both the nad9 gene and the chloroplast-derived sequence, indicating that the nad9 gene was transcribed together with the chloroplast-derived sequence. From the results of in vitro capping and ribonuclease protection experiments, as well as primer extension analysis, we identified at least seven sites for the initiation of transcription of nad9 in the chloroplast-derived sequence. All of the initiation sites for transcription of the nad9 gene were located in sequences homologous to chloroplast DNA. Two of seven initiation sites were flanked by a sequence homologous to the consensus promoter motif that includes the CRTA motif (where R is A or G) of the rice mitochondrion. However, the sequences surrounding the other five sites showed only limited similarity to the conserved sequence. It is suggested that all the promoters of the rice nad9 gene exist in a sequence that was transferred from the chloroplast during evolution. Thus, the chloroplast-derived sequence has a novel, significant function in the mitochondrial genome of this higher plant.
Mol Gen Genet 1996 Sep 25
PMID:A chloroplast-derived sequence is utilized as a source of promoter sequences for the gene for subunit 9 of NADH dehydrogenase (nad9) in rice mitochondria. 887 37

RNA polymerase II contains a ribonuclease activity which is stimulated by the transcription elongation factor SII. This nuclease shortens the nascent RNA and facilitates relief of transcriptional arrest by allowing the enzyme to make multiple attempts to read through an obstacle to transcription. The catalytic center of this ribonuclease is unknown, although a region of the enzyme's second largest subunit shares local sequence similarly with barnase and other bacterial ribonucleases. To test the role of the barnase homology region in SII-activated cleavage, we engineered a single amino acid change in the Saccharomyces cerevisiae enzyme at a position homologous to a catalytic residue of barnase (Glu-371) and has been suggested as a participant in active site chemistry of RNA polymerase II. We purified RNA polymerase II from mutant yeast and assayed its ability to cleave and re-extend the nascent RNA following SII treatment. We find no defects in this function of the mutant enzyme, suggesting that the barnase homology region does not represent the active site of the SII-activated nuclease. These mutant yeast cells were also resistant to mycophenolic acid, which slows the growth of some yeast mutants bearing elongation defective RNA polymerase II or mutant elongation factor SII.
Mol Gen Genet 1997 Jan 27
PMID:Glutamic acid-371 of the barnase homology domain in RNA polymerase II is not required for SII-activated RNA cleavage. 903 12

When MDCK cells in a semiconfluent monolayer were infected with 5 p.f.u. per cell of influenza virus A/PR/8/34 (H1N1), a majority of the cells continued to grow stably upon subsequent cultivation with a growth medium containing 50% foetal calf serum. While growing, the cells spontaneously excreted virus, the amount of which declined gradually as the passage number of the cells increased. The extent of virus shedding was significantly increased when the cells were subsequently maintained in a medium containing 0.2% bovine serum albumin. Within the cells, viral messenger RNAs for all eight genes of A/PR/8 were demonstrated by PCR indicating that endogenous viral genes were constitutively transcribed. However, viral proteins as well as viral genes were not demonstrable by radioimmunoprecipitation or ribonuclease protection assays, respectively.
J Gen Virol 1997 Mar
PMID:Spontaneous excretion of virus from MDCK cells persistently infected with influenza virus A/PR/8/34. 904 5

The beta subunit of thyroid-stimulating hormone (TSHbeta) has been isolated and sequenced in many species, including several mammals and the frog, but not in any avian species. Therefore, the objective of this study was to isolate and sequence a cDNA for chicken TSHbeta. Degenerate oligonucleotide primers were designed, based on conserved regions of TSHbeta from four other species, and used for reverse transcription and polymerase chain reaction amplification of a cDNA fragment from total cellular RNA of pituitary glands from 7-day-old chicks. The remaining sequence was completed by rapid amplification of cDNA ends. The predicted amino acid sequence was 70. 4% identical between bovine and chicken, 69.6% identical between chicken and rat, and 57.4% identical between chicken and frog. To test for tissue specificity of the cDNA, total cellular RNA samples from testicle, liver, pituitary, lung, and heart were analyzed by Northern blot. The 32P-labeled antisense riboprobe hybridized to an RNA species of approximately 600-700 bases in pituitary RNA alone, corresponding with the length of TSHbeta mRNA in other species. Gene expression in Day 1 posthatch chickens was then analyzed by ribonuclease protection assay. Anterior pituitary cells of Day 1 chickens were treated for 20 to 24 hr in serum-free medium alone or with medium containing either thyrotropin-releasing hormone (TRH) (10(-8) M) or triiodothyronine (T3) (10(-9) M). The RNA was then harvested from these cells and hybridized with a 32P-labeled antisense riboprobe. Treatment with TRH had no effect on TSHbeta mRNA levels, while T3 significantly decreased (P < 0.05; n = 6 trials) TSHbeta mRNA levels by 45%. Taken together these results indicate that the cDNA sequence derived represents chicken TSHbeta mRNA, and that TSHbeta gene expression is downregulated by thyroid hormones as it is in mammals.
Gen Comp Endocrinol 1997 Aug
PMID:Cloning and sequence analysis of a cDNA for the beta subunit of chicken thyroid-stimulating hormone. 924 26

Hammerhead ribozymes were used as substrates to examine endoribonucleolytic activities in cell extracts and cultured human cells. Primer-extension analyses showed that ribozymes directed against tumor necrosis factor-alpha mRNA and human immunodeficiency virus type 1 tat mRNA were cleaved at UA and CA dinucleotides by extracts. Preferred cleavage sites were similar to those observed following digestion with RNase A, and cleavage was blocked by RNasin, an inhibitor of pyrimidine-specific ribonucleases. Removal of UA and CA dinucleotides rendered ribozymes more stable when incubated in cell extracts that were not significantly contaminated by extracellular nucleases. Placement of UA dinucleotides adjacent to a ribozyme in mRNA led to excision of the ribozyme from long transcripts during incubation in extracts. UA dinucleotides also made mRNA more labile than a control RNA when expressed from an endogenous plasmid gene in the human myeloid cell line U937. Similarly, UA and CA dinucleotides caused ribozymes to have a shorter half-life when delivered to U937 cells by lipofectin-mediated transformation. Taken together, these data indicate that one or more members of the pyrimidine-specific ribonuclease family is involved in the intracellular degradation of RNA, and they explain the paucity of UA dinucleotides in eukaryotic mRNA. Judicious manipulation of preferred target sequences of pyrimidine-specific ribonucleases may be useful in designing effective hammerhead ribozymes.
Mol Gen Genet 1998 May
PMID:Degradation of hammerhead ribozymes by human ribonucleases. 964 39

The expression of insulin-like growth factor-1 (IGF-1) was examined in subcutaneous (SQ) adipose tissue from 105-day pig fetuses by ribonuclease protection assays and in situ hybridization using a porcine IGF-1 riboprobe. Fetuses were hypophysectomized (hypox) at 70 days of gestation and at 90 days thyroxine (T4) pellets were implanted into some of the hypox fetuses. Fetuses were removed and SQ tissues collected on day 105 of gestation. RNase protection assays followed by scanning laser densitometry revealed that IGF-1 mRNA in SQ adipose tissue in hypox fetuses was significantly decreased to 19.8 +/- 1.2% of control values. T4 treatment increased the expression of IGF-1 by 174 +/- 26.6% of values for hypox fetuses. Using in situ hybridization we showed that fetal hypophysectomy reduced and T4 treatment increased expression of IGF-1 mRNA in the outer SQ adipose tissue layer (P < 0.05). However, T4 treatment after hypox did not influence IGF-1 expression in the inner SQ layer (P > 0.05). IGF-1 was expressed around capillaries, in small fat cells, and in fibroblasts in loose and dense connective tissue. Large fat cells, however, did not express IGF-1. Collectively, we concluded that (1) IGF-1 mRNA was decreased after hypox and increased by T4 treatment in SQ tissue of 105-day fetuses; (2) The expression of the IGF-1 gene was more sensitive to T4 treatment after hypox in outer SQ tissue than in inner SQ tissue; (3) Most stromal cells produced IGF-1 mRNA, and as a result they may influence adipogenesis in the outer layer of SQ adipose tissue; and (4) Once fat cells enlarged, expression of IGF-1 was not detected. Therefore, these studies provide evidence that IGF-1 may mediate the influence of T4 on fetal adipogenesis.
Gen Comp Endocrinol 1998 Oct
PMID:The expression of insulin-like growth factor-1 during adipogenesis in vivo: effect of thyroxine. 974 1

Plasmid vectors for positive selection of cloned inserts in Escherichia coli were devised, based on an expression plasmid (pMT416) for the bacterial ribonuclease barnase. In addition to the barnase gene under control of a synthetic tac promoter, these plasmids carry the gene for the barnase inhibitor, barstar, the constitutive expression of which protects the bacterium from the detrimental effects of moderate barnase production. Full expression of the barnase gene overcomes protection by barstar and becomes lethal. Having a unique SmaI/XmaI site in the barnase structural gene, pMT416 itself can be used as a selective vector: uncut or religated pMT416 will preclude growth while plasmids with inserts in the barnase gene will allow the cells to survive. The entire pUC polylinker was inserted into the barnase gene in place of the Val-36 codon. This insert of nineteen largely hydrophilic amino acids does not prevent the lethal effect of full expression of the gene. The resulting plasmid, pMT440, is a generally useful selective cloning vector representing the "kill-the-rest" approach.
Mol Gen Genet 1998 Sep
PMID:Ribonuclease-charged vector for facile direct cloning with positive selection. 979 May 92


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