Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Spliced leader (SL) trans-splicing generates the 5' end of mature mRNAs through the addition of a small exon to pre-mRNAs in some flagellates (kinetoplastida and euglenoids) and metazoans (nematodes and flatworms). Although SL addition in the kinetoplastida and a subset of nematode genes serves to resolve multicistronic mRNAs into monocistronic, capped mRNAs, information regarding the functional significance of trans-splicing in flatworms is limited. We describe here the identification and characterization of a closely linked gene upstream from the trans-spliced enolase gene in the flatworm Schistosoma mansoni. This gene produces a non-trans-spliced mRNA encoding a ubiquinol binding protein, UbCRBP, that is a component of the ubiquinol-cytochrome C reductase complex. The distance between the UbCRBP polyadenylation site and the enolase trans-splice acceptor site is exceptionally short, only 54 nucleotides. Primer extension (5' RACE), RT-PCR, and RNase mapping have identified steady state, cis-spliced RNAs which significantly overlap both the UbCRBP and enolase genes. These transcripts contain the 5' ends of mature UbCRBP mRNAs; extend through UbCRBP, across the intergenic region, and a significant distance 3' into the enolase gene. Interestingly, the close linkage between the UbCRBP and enolase genes is conserved in a second flatworm, Fasciola hepatica, which also trans-splices the downstream enolase gene. Taken together, the role of SL addition in resolving multicistronic transcripts in both C. elegans and the kinetoplastida, the conservation of UbCRBP/enolase gene linkage in two divergent trematodes, and the multicistronic organization of schistosome UbCRBP/enolase RNAs are consistent with the suggestion that these two genes are likely to be cotranscribed and that trans-splicing in flatworms may be associated with polycistronic transcripts.
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PMID:Gene linkage and steady state RNAs suggest trans-splicing may be associated with a polycistronic transcript in Schistosoma mansoni. 929 98

To begin to characterize biochemically the transcriptional activation systems in photosynthetic bacteria, the Rhodobacter capsulatus RNA polymerase (RNAP) that contains the sigma70 factor (R. capsulatus RNAP/sigma70) was purified and characterized using two classical sigma70 type promoters, the bacteriophage T7A1 and the RNA I promoters. Transcription from these promoters was sensitive to rifampicin, RNase, and monoclonal antibody 2G10 (directed against the Escherichia coli sigma70 subunit). Specific transcripts were detected in vitro for R. capsulatus cytochrome c2 (cycA) and fructose-inducible (fruB) promoters and genes induced in photosynthesis (puf and puc) and bacteriochlorophyll biosynthesis (bchC). Alignment of these natural promoters activated by R. capsulatus RNAP/sigma70 indicated a preference for the sequence TTGAC at the -35 region for strong in vitro transcription. To test the -35 recognition pattern, the R. capsulatus nifA1 promoter, which exhibits only three of the five consensus nucleotides at the -35 region, was mutated to four and five of the consensus nucleotides. Although the nifA1 wild type promoter showed no transcription, the double mutated promoter exhibited high levels of in vitro transcription by the purified R. capsulatus RNAP/sigma70 enzyme. Similarities and differences between the RNAPs and the promoters of R. capsulatus and E. coli are discussed.
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PMID:Characterization of the Rhodobacter capsulatus housekeeping RNA polymerase. In vitro transcription of photosynthesis and other genes. 934 Nov 73

Exposure to peroxisome proliferators, which are extensively used, causes a number of pleiotrophic effects. Prolonged exposure to the peroxisome proliferator, DEHP, causes hepatic hyperplasia and liver tumors in rats and mice. This exposure can also induce a number of enzymes. To identify additional genes that are regulated by DEHP, mRNA differential display was used. One of the genes affected is cytochrome 450 Cyp2f2, a naphthalene hydroxylase. Using northern analysis, RNase protection assay, and RT-PCR, we show that the Cyp2f2 mRNA levels are decreased in mouse liver following DEHP treatment. A smaller Cyp2f2 mRNA transcript was also detected in kidney and these transcript levels were also suppressed but to a lesser extent than that in the liver. The response to DEHP in mouse liver is both dose and time dependent.
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PMID:Suppression of cytochrome P450 Cyp2f2 mRNA levels in mice by the peroxisome proliferator diethylhexylphthalate. 936 24

Steroidogenic acute regulatory protein (StAR) is a 30-kDa protein involved in the transport of cholesterol to the inner mitochondrial membrane and thus plays a key role in steroid biosynthesis. To clarify the implications of this protein in neurosteroid biosynthesis, we examined the possible expression of a StAR transcript in the adult rat CNS and detected it. cDNA cloning and sequencing analysis revealed that two forms of StAR mRNAs are expressed in the brain in the same manner as in the adrenal gland, indicating that they are fully functional and not minor gene transcripts. An RNase protection assay quantitatively revealed that the amount of the rat StAR transcript in brain was two to three orders of magnitude lower than that in the adrenal gland. An in situ hybridization study, involving antisense riboprobes, revealed that StAR transcripts were abundant in the cerebral cortex, hippocampus, dentate gyrus, olfactory bulb, cerebellar granular layer, and Purkinje cells. Furthermore, other steroidogenic enzymes, side-chain cleavage cytochrome P-450SCC (CYP XIA1) and 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase (EC 1.1.1.145), were found to be coexpressed in the hippocampus, dentate gyrus, cerebellar granular layer, and Purkinje cells. These findings strongly indicate that neurosteroids are synthesized in a region-specific manner in the brain.
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PMID:Steroidogenic acute regulatory protein (StAR) transcripts constitutively expressed in the adult rat central nervous system: colocalization of StAR, cytochrome P-450SCC (CYP XIA1), and 3beta-hydroxysteroid dehydrogenase in the rat brain. 983 20

Determination of protein stability (DeltaGD0) from the conformational transition curve induced by a chemical denaturant is problematic; for different values of DeltaGD0, the value of the Gibbs energy change on denaturation (DeltaGD) in the absence of the denaturant are obtained when different extrapolation methods are used to analyze the same set of (DeltaGD, denaturant concentration) data [Pace, C. N. (1986) Methods Enzymol. 131, 266-280]. We propose a practical solution to this problem and use it to test the dependence of DeltaGD of lysozyme, ribonuclease-A, and cytochrome-c on [urea], the molar urea concentration. This method employs (i) measurements of the urea-induced denaturation in the presence of different guanidine hydrochloride (GdnHCl) concentrations which by themselves disrupt the native state of the protein at the same temperature and pH at which denaturations by urea and GdnHCl have been measured; (ii) estimation of DeltaGDcor, the value of DeltaGD corrected for the effect of GdnHCl on the urea-induced denaturation using the relation (DeltaGDcor = DeltaGD + mg [GdnHCl] = DeltaGD0 - mu [urea], where mg and mu are the dependencies of DeltaGD on [GdnHCl] and [urea], respectively) whose parameters are all determined from experimental denaturation data; and (iii) mapping of DeltaGDcor onto the DeltaGD versus [urea] plot obtained in the absence of GdnHCl. Our results convincingly show that (i) [urea] dependence of DeltaGD of each protein is linear over the full concentration range; (ii) the effect of urea and GdnHCl on protein denaturation is additive; and (iii) KCl affects the urea-induced denaturation if the native protein contains charge-charge interaction and/or anion binding site, in a manner which is consistent with the crystal structure data.
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PMID:Protein stability: functional dependence of denaturational Gibbs energy on urea concentration. 1002 41

We have cloned a 3.6-kb genomic DNA fragment from Pseudomonas aeruginosa harboring the rpoA, rplQ, katA, and bfrA genes. These loci are predicted to encode, respectively, (i) the alpha subunit of RNA polymerase; (ii) the L17 ribosomal protein; (iii) the major catalase, KatA; and (iv) one of two iron storage proteins called bacterioferritin A (BfrA; cytochrome b1 or b557). Our goal was to determine the contributions of KatA and BfrA to the resistance of P. aeruginosa to hydrogen peroxide (H2O2). When provided on a multicopy plasmid, the P. aeruginosa katA gene complemented a catalase-deficient strain of Escherichia coli. The katA gene was found to contain two translational start codons encoding a heteromultimer of approximately 160 to 170 kDa and having an apparent Km for H2O2 of 44.7 mM. Isogenic katA and bfrA mutants were hypersusceptible to H2O2, while a katA bfrA double mutant demonstrated the greatest sensitivity. The katA and katA bfrA mutants possessed no detectable catalase activity. Interestingly, a bfrA mutant expressed only approximately 47% the KatA activity of wild-type organisms, despite possessing wild-type katA transcription and translation. Plasmids harboring bfrA genes encoding BfrA altered at critical amino acids essential for ferroxidase activity could not restore wild-type catalase activity in the bfrA mutant. RNase protection assays revealed that katA and bfrA are on different transcripts, the levels of which are increased by both iron and H2O2. Mass spectrometry analysis of whole cells revealed no significant difference in total cellular iron levels in the bfrA, katA, and katA bfrA mutants relative to wild-type bacteria. Our results suggest that P. aeruginosa BfrA may be required as one source of iron for the heme prosthetic group of KatA and thus for protection against H2O2.
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PMID:Bacterioferritin A modulates catalase A (KatA) activity and resistance to hydrogen peroxide in Pseudomonas aeruginosa. 1036 48

Accumulating evidence from human and experimental animal studies indicates that consumption of heterocyclic amines (HA), derived from cooked meat and fish, may be associated with an increased incidence of cancer. Experiments were initiated to assess the role of one of these compounds, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), as a potential transplacental carcinogen, as well as to evaluate whether in utero exposure to IQ results in the induction of fetal cytochrome P4501A1 (Cyp1a1), P4501B1 (Cyp1b1), and/or glutathione S-transferase (GST). Inducible, or responsive, backcrossed fetuses resulting from a cross between congenic C57BL/6 (Ah(d)Ah(d)) nonresponsive female mice and C57BL/6 (Ah(b)Ah(b)) responsive male mice were transplacentally exposed to olive oil or 6.25, 12.5, or 25 mg/kg of IQ on day 17 of gestation. No macroscopically or microscopically visible liver, lung, or colon tumors were found in the transplacentally treated offspring by one year after birth. Ethoxyresorufin O-deethylase (EROD) and 1-chloro-2,4-dinitrobenzene assays were performed to evaluate whether transplacental exposure to IQ results in the induction of fetal Cyp1a1 and GST, respectively, in lung and liver tissues. Results showed levels of EROD and GST activity in tissues of IQ-treated mice to be very close, if not identical, to those of mice treated with olive oil. Similarly, ribonuclease protection assay data showed that the levels of Cyp1a1 and Cyp1b1 RNA in tissues of IQ-treated mice were not significantly different from those of oil-treated controls. Previous studies have shown that the developing organism expresses very low levels of Cyp1a2. Thus, in utero exposure to IQ does not lead to induction of Cyp1a1, Cyp1a2, or Cyp1b1 in the fetal compartment, thereby maintaining the low levels of these activating enzymes in the developing organism. Taken together, these data imply that, at least under the conditions employed for these experiments, IQ may not play an important role in transplacentally induced tumorigenesis.
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PMID:Prenatal toxicity and lack of carcinogenicity of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) following transplacental exposure. 1082 74

In vertebrates, the growth and maturation of the ovarian follicle is dependent on the appropriate dynamics of sex steroid secretion, which is dictated by gene expression of the steroidogenic enzymes. The molecular aspects of steroid regulation are poorly understood in fishes, so as a first step we determined the pattern of expression of four key steroidogenic genes throughout the ovarian cycle in an annually spawning teleost, the channel catfish (Ictalurus punctatus). The abundance of transcripts encoding 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and cholesterol side chain cleavage (P450(scc)), 17 alpha-hydroxylase/lyase (P450(c17)), and aromatase (P450(arom)) were determined by rtqRT-PCR or ribonuclease protection assay and correlated to ovarian growth and plasma titers of estradiol (E(2)) and testosterone (T) in two populations of catfish. Elevations in transcript abundance for P450(c17), P450(scc), and P450(arom) were observed at the onset of ovarian recrudescence and during early vitellogenic growth of the oocytes; however, all three decreased precipitously with the completion of vitellogenesis. Changes in the expression of these genes strongly suggest a direct correlation to E(2) and T titers. Alternatively 3 beta-HSD transcript abundance was relatively stable throughout the year. This study suggests that the genes encoding the three steroidogenic cytochrome P450s have a similar regulatory mechanism.
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PMID:Changes in the expression of genes encoding steroidogenic enzymes in the channel catfish (Ictalurus punctatus) ovary throughout a reproductive cycle. 1109 Apr 35

Based on inorganic matrix controlled pore glass (CPG) and macro-pore silica sphere, by using polyethylene glycol (PEG 1000) as a ligand, a preparation method of hydrophobic interaction chromatographic (HIC) packing material was improved by adding a proper catalyst during the bonding process. The packing material can be synthesized in a scale-up batch, for example 150g for each batch, both for analytical and preparative columns. The retention of proteins, such as cytochrome C (Cyt-C), chymotrypsingen-A (Chy-A), lysozyme (Lys) and ribonuclease(Rnase), is increased with the increasing of (NH4)2SO4 concentration in the eluant 2.5 mol/L of salt concentration for the mobile phase was chosen by considering the separation efficiency and equipment life. After comparing the effect of pH for the retention of proteins it is found that the proteins are well separated at pH 7. The time of linear gradient elution program was optimized in considering the separation efficiency and speed. It is better to take 30 minutes of the gradient program for the separation. Six standard proteins can be well separated with the high-performance HIC column in the linear gradient elution program from 2.5 to 0 mol/L of (NH4)2SO4 in 50 mmol/L of phosphate buffer solution within 30 minutes. Cyt-C, Rnase, Lys and Chy-A can be separated by the HIC column based on CPG matrix. Six proteins, Cyt-C, Rnase, Lys, Chy-A, insulin(Ins) and lipase (Lip) can be well separated on the column based on silica matrix with gradient elution program. The recovery of trypsin detected with BAEE method is over 95% after purification with the HIC column.
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PMID:[Scale-up preparation of hydrophobic interaction chromatographic packing materials based on inorganic matrix]. 1573 63

The pathophysiology of sepsis-induced myocardial dysfunction still remains controversial. Macrophage migration inhibitory factor (MIF) has recently been identified as a cardiac-derived myocardial depressant factor in septic shock. Putative mechanisms by which MIF affects cardiac function are unknown. In an investigation of possible mechanisms of action, a rat model of endotoxin toxicity was designed using intraperitoneal (I/P) injection of lipopolysaccharides (LPS) with or without coinfusion of neutralizing anti-MIF or isotypic-matched antibodies. Echocardiographic evaluation revealed that MIF neutralization reversed endotoxin-induced myocardial dysfunction at 24 hours after injection. RNase protection assay (RPA) and Western blot established that MIF neutralization prevented LPS-induced mRNA expression and production of heart-derived inflammatory paracrine and autocrine cytokines such as IL-1s and IL-6. Moreover, MIF immunoneutralization increased heart Bcl-2/Bax protein ratio and suppressed endotoxin-induced release of mitochondrial cytochrome-c, as demonstrated by Western blotting. Inhibition of mitochondrial loss of cytochrome-c decreased in heart caspase-3 activity at 6 and 24 hours after injection. MIF neutralization also restored the LPS-induced deficient nuclear translocation of phospho-Akt and consequently the expression of the heart survival nuclear factor GATA-4. The restoration of the translocation/expression of survival factors by MIF inhibition resulted in lowered endotoxin-induced DNA fragmentation at 24 hours, a hallmark of downstream cardiomyocyte apoptosis. Our data indicate that early inactivation of MIF significantly reverses the imbalance of proapoptotic to prosurvival pathways and reduces acute inflammation of the heart thereby improving myocardial dysfunction induced by endotoxin.
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PMID:Endotoxin-induced myocardial dysfunction: effects of macrophage migration inhibitory factor neutralization. 1587 12


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