Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.3 (RNase T1)
 1,228 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Highly purified tRNAPhe from rabbit liver, calf liver and bovine liver were completely digested with pancreatic ribonuclease and ribonuclease T1. The oligonucleotides were separated and identified. The tRNAPhe from rabbit liver and calf liver were partially cleaved with ribonuclease T1 or by action of lead acetate. We describe the analyses of the large fragments and the derivation of the primary structure of these mammalian tRNAsPhe.
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PMID:The primary structure of rabbit, calf and bovine liver tRNAPhe. 41 81

Ribonuclease T1 was purified from an Escherichia coli overproducing strain and co-crystallized with adenosine 2'-monophosphate (2'-AMP) by microdialysis against 50% (v/v) 2-methyl-2,4-pentanediol in 20 mM sodium acetate, 2 mM calcium acetate, pH 4.2. The crystals have orthorhombic space group P2(1)2(1)2(1), with cell dimensions a = 48.93(1), b = 46.57(4), c = 41.04(2) A; Z = 4 and V = 93520 A3. The crystal structure was determined on the basis of the isomorphous structure of uncomplexed RNase T1 (Martinez-Oyanedel et al. (1991) submitted for publication) and refined by least squares methods using stereochemical restraints. The refinement was based on Fhkl of 7,445 reflections with Fo greater than or equal to 1 sigma (Fo) in the resolution range of 10-1.8 A, and converged at a crystallographic R factor of 0.149. The phosphate group of 2'-AMP is tightly hydrogen-bonded to the side chains of the active site residues Tyr38, His40, Glu58, Arg77, and His92, comparable with vanadate binding in the respective complex (Kostrewa, D., Choe, H.-W., Heinemann, U., and Saenger, W. (1989) Biochemistry 28, 7592-7600) and different from the complex with guanosine 2'-monophosphate (Arni, R., Heinemann, U., Tokuoka, R., and Saenger, W. (1988) J. Biol. Chem. 263, 15358-15368) where the phosphate does not interact with Arg77 and His92. The adenosine moiety is not located in the guanosine recognition site but stacked on Gly74 carbonyl and His92 imidazole, which serve as a subsite, as shown previously (Lenz, A., Cordes, F., Heinemann, U., and Saenger, W. (1991) J. Biol. Chem. 266, 7661-7667); in addition, there are hydrogen bonds adenine N6H . . . O Gly74 (minor component of three-center hydrogen bond) and adenosine O5' . . . O delta Asn36. These binding interactions readily explain why RNase T1 has some affinity for 2'-AMP. The molecular structure of RNase T1 is only marginally affected by 2'-AMP binding. Its "empty" guanosine-binding site features a flipped Asn43-Asn44 peptide bond and the side chains of Tyr45, Glu46 adopt conformations typical for RNase T1 not involved in guanosine binding. The side chains of amino acids Leu26, Ser35, Asp49, Val78 are disordered. The disorder of Val78 is of interest since this amino acid is located in a hydrophobic cavity, and the disorder appears to be correlated with an "empty" guanosine-binding site. The two Asp15 carboxylate oxygens and six water molecules coordinate a Ca2+ ion 8-fold in the form of a square antiprism.
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PMID:Crystal structure of ribonuclease T1 complexed with adenosine 2'-monophosphate at 1.8-A resolution. 165 20

We have investigated the RNA structure of the region surrounding the muscle-specific exon 6B of the chicken beta-tropomyosin gene. We have used a variety of chemical and enzymatic probes: dimethylsulfate, N-cyclohexyl-N'-(2-(N-methylmorpholino)-ethyl)-carbodiimide-p-tolu enesulfonate) , RNase T1 and RNase V1. Lead acetate was also used to obtain some information on the tertiary structure of this region. Probing the wild-type sequence suggests a model involving one-stem and three-stem-loop structures in and around this exon. Two of these, hairpin I and stem III, have previously been implicated in repression of splicing of the intron following exon 6B in a HeLa nuclear extract. Stem I includes sequences at the beginning of exon 6B and stem III results from interaction of the intron upstream from exon 6B with sequences in the middle of the intron downstream from this exon (the intron whose splicing is repressed). Neither stem I nor stem III directly involves the consensus sequences (5' splice site, branch-point, 3' splice site) of the repressed intron. Probing RNAs that are derepressed for splicing of this intron show that there are structural changes around the 5' splice site and branch-point sequence that correlate with the derepression. This is true, despite the fact that the derepressed RNAs are altered in a region far from these consensus sequences. The most striking structural correlation with splicing capacity of the intron downstream from exon 6B is seen by probing with lead acetate. Lead ions cut RNA at specific residues; these sites are very sensitive to RNA tertiary structure. Repressed and derepressed RNAs show entirely different cleavage patterns after incubation with lead acetate. Remarkably, hybridizing a derepressed RNA with an RNA comprising the ascending arm of stem III not only re-establishes repression, but also converts the pattern of susceptibility to attack by lead ions over the whole molecule. We suggest that RNA conformation plays a role in keeping exon 6B from being spliced into non-muscle cell mRNA.
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PMID:Determination of an RNA structure involved in splicing inhibition of a muscle-specific exon. 194 33

Ribonuclease (RNase) F1 was inactivated by incubation with an excess amount of iodoacetate at pH 5.5, 37 degrees C according to pseudo first-order kinetics. It was protected to various degrees, from inactivation by nucleotides, among which guanosine 2'-phosphate was most effective. The pseudo first-order rate constant was proportional to the reagent concentration, indicating that the reaction in reality follows second-order kinetics. The second-order rate constant was determined to be 25 x 10(-4) M-1 s-1. The inactivation rate was maximal at pH 5.5-6.0. When iodo[2-14C]acetate was used as the reagent, the stoichiometry of incorporation was determined to be 1.1 mol carboxymethyl group per mol of RNase F1 and glutamic acid residue 58 was assigned as the site of modification.
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PMID:Carboxymethylation of an active site glutamic acid residue of ribonuclease F1 iodoacetate. 256 96

Ribonuclease T1 was crystallized under various conditions. Form I crystals were produced by microdialysis against 53% (v/v) 2-methyl-2,4-pentanediol in 0.01 M sodium acetate, 0.05% 2'-guanylic acid (2'GMP) and 0.02% NaN3 (pH 6.2-7.2). These crystals are tetragonal, space group P41212 and contain two molecules per asymmetric unit; cell dimensions are a = b = 5.86 nm, c = 13.28 nm. Form IIa and form IIb crystals were obtained by microdialysis from a buffer of 0.01-0.05 M sodium acetate, 0.25-0.5% 2'GMP, 0.02% NaN3 and 2-5 mM calcium acetate (pH 4.0-4.4) in the presence of 50-75% (v/v) 2-methyl-2,4-pentanediol. These crystals are orthorhombic, space group P212121, and contain one molecule per asymmetric unit; cell dimensions are a = 4.66 nm, b = 5.02 nm, c = 4.04 nm (form I) and alpha = 4.44 nm, b = 5.00 nm, c = 4.03 nm (form II). Using high-performance liquid chromatography, it could be shown for all crystal forms that 2'-GMP is bound in the crystals. The molecular ratio between RNase T1 and 2'GMP was 0.9 for form II crystals and thus agreed with a 1:1 enzyme-nucleotide complex. Heavy-atom derivatives were produced with lead acetate for form IIa crystals and with uranyl acetate for from IIb crystals. Three-dimensional X-ray analysis of the RNase-T1 x 2'GMP complex is under way.
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PMID:Crystallization of a complex between ribonuclease T1 and 2'-guanylic acid. 625 Aug 34

The three-dimensional structure of Ribonuclease St (RNase St), the extracellular ribonuclease from Streptomyces erythreus, has been deduced based on a preliminary electron density map at 2.5 A resolution. RNase St has a substrate specificity similar to ribonuclease T1 which catalyzes the splitting of the phosphodiester bond of guanylic acid. Crystals grown as diamond plates have space group C2 with unit cell parameters a=88.4, b=33.0, c=69.0 A, beta = 98.4 degrees having two enzyme molecules per asymmetric unit. Phases were obtained by use of KAu(CN)4, phenylmercuric acetate and UO2 (CH3COO)2. The overall dimensions of the molecule are 40 X 30 X 25 A. The most prominent secondary structural features are two turns of alpha-helix and a three strand stretch of antiparallel beta-sheet. The alpha-carbon backbone of RNase St seems to have no apparent correlation with that of ribonuclease A.
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PMID:Preliminary crystal structure analysis of a microbial, guanine-specific ribonuclease St at 2.5 A resolution. 679 45

Effects of medium viscosity on kinetic parameters of poly(U) hydrolysis catalyzed by RNase from Bac. intermedius 7P (binase) were studied in solutions of sucrose (4-50 wt. %) and glycerol (35-62 wt. %) in Tris--sodium acetate buffer (pH 7.5) at 25 degreesC. The rate constant of reaction kcat was practically unchanged over a wide range of viscosities (1-15 cP for sucrose and 2.5-3 cP for glycerol). In glycerol solutions, kcat slightly increased with viscosity increase from 4 to 10 cP. Addition of NaCl to the buffer medium resulted in an inhibitory effect of Na+ on kcat, prevented by 50% sucrose or 60% glycerol. It is concluded that binase-catalyzed poly(U) cleavage occurs through a "tense"-substrate mechanism, similarly to reactions catalyzed by alpha-chymotrypsin, trypsin, and laccase.
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PMID:Effects of medium viscosity on kinetics of the enzymatic reaction catalyzed by bacterial RNase 986 66

We have previously demonstrated that phorbol myristate acetate (PMA) up-regulates H-ferritin gene expression in myeloid cells by stabilization of its message. In the present report, we showed that insertion of the 3'-untranslated region (3'-UTR) of H-ferritin mRNA at the 3'-end of luciferase coding sequence significantly reduced the stability of luciferase mRNA in human monocytic THP-1 cells. However, the half-life of the chimeric transcript was markedly prolonged after PMA treatment. A cytosolic protein factor from THP-1 cells was found to specifically bind to H-ferritin 3'-UTR. PMA treatment of THP-1 cells resulted in the reduction of the RNA binding activity in a time-dependent manner. Deletion analysis and RNase T1 mapping revealed a pyrimidine-rich sequence within the 3'-UTR which interacts with the protein factor. Competition experiments with homoribopolymers further demonstrated the importance of uridines for the binding activity. Point mutations in uridines of the pyrimidine-rich sequence reduced the protein binding to 3'-UTR, while increasing the stability of the chimeric luciferase transcript. Together, these results demonstrate that the pyrimidine-rich sequence in the 3'-UTR is involved in post-transcriptional regulation of H-ferritin gene expression in myeloid cells.
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PMID:Post-transcriptional regulation of H-ferritin mRNA. Identification of a pyrimidine-rich sequence in the 3'-untranslated region associated with message stability in human monocytic THP-1 cells. 1051 12