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

In Anacystis nidulans, upon infection with cyanophage AS-1, after a lag period of 1 h the level of deoxyribonuclease (DNase) activity increaded rapidly up to 15- to 20-fold in 4 to 5 h in the light. In contrast, the ribonuclease and phosphomonoesterase activities increased significantly only 4 to 5 h after infection, i.e. as late as 1 h prior to lysis. In complete darkness, the nuclease levels remained unaltered. However, when the infected cells were exposed to light for 1 or 2 h after infection, the DNase level increased essentially to the same extent in the dark as in continuous light, although the complete replication cycle of the virus was impaired in the dark and cells lysed only in the continuously illuminated cultures. Inhibition of photosystem II with 3-(3,4-dichlorophenyl)-1-dimethylurea during the early illumination period strongly decreased the subsequent, infection-dependent increase in DNase activity in the dark. The virus-induced increase in DNase activity was also inhibited by chloramphenicol. The data suggest that, in spite of the obligate photoautotrophic nature of A. nidulans, dark metabolism is able to support fully the formation of some specific proteins if the triggering of their synthesis takes place in light.
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PMID:Formation in the dark, of virus-induced deoxyribonuclease activity in Anacystis nidulans, an obligate photoautotroph. 17

RNA ligase has been highly purified in good yields from bacteriophage T4-infected Escherichia coli by a rapid and reproducible procedure. The enzyme is free of phosphomonoesterase and ribonuclease activities and is therefore suitable for the synthesis of oligoribonucleotides and for the labeling of the 3'-terminus of RNA. Greater than 90% of the protein in the enzyme preparation migrates as a single band on gradient polyacrylamide gels containing sodium dodecyl sulfate during electrophoresis. For use as a DNA synthesis reagent the enzyme may be reliably freed of deoxyribonuclease activity by an additional chromatographic procedure using a commercially avialable resin.
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PMID:The purification of nuclease-free T4-RNA ligase. 21 95

A ribonuclease (ribonucleate 3-pyrimidine-oligonucleotidohydrolase, EC 3.1.4.22) was purified 8300-fold from soluble fraction of beef brain and its properties were investigated. The enzyme is an endonuclease capable of hydrolyzing tRNA, rRNA, poly(C), but shows no activity towards poly(U), poly(A), and poly(G). The preparation is free of deoxyribonuclease, non-specific phosphodiesterase and phosphomonoesterase activity. The enzyme has a pH optimum of 7.6, is not heat stable, has a molecular weight of 25 000, and has a K-m of 134 mu rRNA and K-m of 1600 mug poly(C) per ml.
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PMID:Purification of an alkaline ribonuclease from soluble fraction of beef brain. 23 61

The addition of microelements (Co2+, Cu2+, Zn2+, and Fe2+) to a cultivation medium increased the activity of phosphomonoesterase but not of proteinase and ribonuclease. Glucose and inorganic phosphate (Pi) were the main factors that affected the direction and intensity of the biosynthesis of extracellular enzymes.
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PMID:[Regulation of biosynthesis of intracellular enzymes in Bacillus intermedius 3S-19]. 747 35

The repair of DNA requires the removal of abasic sites, which are constantly generated in vivo both spontaneously and by enzymatic removal of uracil, and of bases damaged by active oxygen species, alkylating agents and ionizing radiation. The major apurinic/apyrimidinic (AP) DNA-repair endonuclease in Escherichia coli is the multifunctional enzyme exonuclease III, which also exhibits 3'-repair diesterase, 3'-->5' exonuclease, 3'-phosphomonoesterase and ribonuclease activities. We report here the 1.7 A resolution crystal structure of exonuclease III which reveals a 2-fold symmetric, four-layered alpha beta fold with similarities to both deoxyribonuclease I and RNase H. In the ternary complex determined at 2.6 A resolution, Mn2+ and dCMP bind to exonuclease III at one end of the alpha beta-sandwich, in a region dominated by positive electrostatic potential. Residues conserved among AP endonucleases from bacteria to man cluster within this active site and appear to participate in phosphate-bond cleavage at AP sites through a nucleophilic attack facilitated by a single bound metal ion.
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PMID:Structure and function of the multifunctional DNA-repair enzyme exonuclease III. 788 81

Snake envenomation employs three well integrated strategies: prey immobilization via hypotension, prey immobilization via paralysis, and prey digestion. Purines (adenosine, guanosine and inosine) evidently play a central role in the envenomation strategies of most advanced snakes. Purines constitute the perfect multifunctional toxins, participating simultaneously in all three envenomation strategies. Because they are endogenous regulatory compounds in all vertebrates, it is impossible for any prey organism to develop resistance to them. Purine generation from endogenous precursors in the prey explains the presence of many hitherto unexplained enzyme activities in snake venoms: 5'-nucleotidase, endonucleases (including ribonuclease), phosphodiesterase, ATPase, ADPase, phosphomonoesterase, and NADase. Phospholipases A(2), cytotoxins, myotoxins, and heparinase also participate in purine liberation, in addition to their better known functions. Adenosine contributes to prey immobilization by activation of neuronal adenosine A(1) receptors, suppressing acetylcholine release from motor neurons and excitatory neurotransmitters from central sites. It also exacerbates venom-induced hypotension by activating A(2) receptors in the vasculature. Adenosine and inosine both activate mast cell A(3) receptors, liberating vasoactive substances and increasing vascular permeability. Guanosine probably contributes to hypotension, by augmenting vascular endothelial cGMP levels via an unknown mechanism. Novel functions are suggested for toxins that act upon blood coagulation factors, including nitric oxide production, using the prey's carboxypeptidases. Leucine aminopeptidase may link venom hemorrhagic metalloproteases and endogenous chymotrypsin-like proteases with venom L-amino acid oxidase (LAO), accelerating the latter. The primary function of LAO is probably to promote prey hypotension by activating soluble guanylate cyclase in the presence of superoxide dismutase. LAO's apoptotic activity, too slow to be relevant to prey capture, is undoubtedly secondary and probably serves principally a digestive function. It is concluded that the principal function of L-type Ca(2+) channel antagonists and muscarinic toxins, in Dendroaspis venoms, and acetylcholinesterase in other elapid venoms, is to promote hypotension. Venom dipeptidyl peptidase IV-like enzymes probably also contribute to hypotension by destroying vasoconstrictive peptides such as Peptide YY, neuropeptide Y and substance P. Purines apparently bind to other toxins which then serve as molecular chaperones to deposit the bound purines at specific subsets of purine receptors. The assignment of pharmacological activities such as transient neurotransmitter suppression, histamine release and antinociception, to a variety of proteinaceous toxins, is probably erroneous. Such effects are probably due instead to purines bound to these toxins, and/or to free venom purines.
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PMID:Ophidian envenomation strategies and the role of purines. 1173 31

DNA ligase D (LigD) catalyzes end-healing and end-sealing steps during nonhomologous end joining in bacteria. Pseudomonas aeruginosa LigD consists of a central ATP-dependent ligase domain fused to a C-terminal polymerase domain and an N-terminal 3'-phosphoesterase (PE) module. The PE domain catalyzes manganese-dependent phosphodiesterase and phosphomonoesterase reactions at a duplex primer-template with a short 3'-ribonucleotide tract. The phosphodiesterase, which cleaves a 3'-terminal diribonucleotide to yield a primer strand with a ribonucleoside 3'-PO4 terminus, requires the vicinal 2'-OH of the penultimate ribose. The phosphomonoesterase converts the terminal ribonucleoside 3'-PO4 to a 3'-OH. Here we show that the PE domain has a 3'-phosphatase activity on an all-DNA primer-template, signifying that the phosphomonoesterase reaction does not depend on a 2'-OH. The distinctions between the phosphodiesterase and phosphomonoesterase activities are underscored by the results of alanine-scanning, limited proteolysis, and deletion analysis, which show that the two reactions depend on overlapping but nonidentical ensembles of protein functional groups, including: (i) side chains essential for both ribonuclease and phosphatase activity (His-42, His-48, Asp-50, Arg-52, His-84, and Tyr-88); (ii) side chains important for 3'-phosphatase activity but not for 3' ribonucleoside removal (Arg-14, Asp-15, Glu-21, Gln-40, and Glu-82); and (iii) side chains required selectively for the 3'-ribonuclease (Lys-66 and Arg-76). These constellations of critical residues are unique to LigD-like proteins, which we propose comprise a new bifunctional phosphoesterase family.
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PMID:Essential constituents of the 3'-phosphoesterase domain of bacterial DNA ligase D, a nonhomologous end-joining enzyme. 1604 7

DNA ligase D (LigD) performs end remodeling and end sealing reactions during nonhomologous end joining in bacteria. Pseudomonas aeruginosa LigD consists of a central ATP-dependent ligase domain fused to a C-terminal polymerase domain and an N-terminal phosphoesterase (PE) module. The PE domain catalyzes manganese-dependent phosphodiesterase and phosphomonoesterase reactions at the 3' end of the primer strand of a primer-template. The phosphodiesterase cleaves a 3'-terminal diribonucleotide to yield a primer strand with a ribonucleoside 3'-PO4 terminus. The phosphomonoesterase converts a terminal ribonucleoside 3'-PO4 or deoxyribonucleoside 3'-PO4 of a primer-template to a 3'-OH. Here we report that the phosphodiesterase and phosphomonoesterase activities are both dependent on the presence and length of the 5' single-strand tail of the primer-template substrate. Although the phosphodiesterase activity is strictly dependent on the 2'-OH of the penultimate ribose, it is indifferent to a 2'-OH versus a2'-H on the terminal nucleoside. Incision at the ribonucleotide linkage is suppressed when the 2'-OH is moved by 1 nucleotide in the 5' direction, suggesting that LigD is an exoribonuclease that cleaves the 3'-terminal phosphodiester. We report the effects of conservative amino acid substitutions at residues: (i) His42, His48, Asp50, Arg52, His84, and Tyr88, which are essential for both the ribonuclease and 3'-phosphatase activities; (ii) Arg14, Asp15, Glu21, and Glu82, which are critical for 3'-phosphatase activity but not 3'-ribonucleoside removal; and (iii) at Lys66 and Arg76, which participate selectively in the 3'-ribonuclease reaction. The results suggest roles for individual functional groups in metal binding and/or phosphoesterase chemistry.
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PMID:Substrate specificity and structure-function analysis of the 3'-phosphoesterase component of the bacterial NHEJ protein, DNA ligase D. 1654 Apr 77

A ribonuclease which was previously shown to be located in isolated vacuoles from suspension-cultured cells of tomato (Lycopersicon esculentum L.; Abel and Glund 1986, Physiol. Plant. 66, 79-86) has been purified to near homogeneity. Purification was up to 55000-fold with a yield of about 20%. The vacuolar origin of the protein was evidenced by comparing its electrophoretic mobility, isoelectric point, pH-optimum for activity and other properties with that of the RNA-degrading activity present in isolated vacuoles. The molecular weight of the native single polypeptide chain was estimated at 17500 and 20300 by gel filtration and sedimentation analysis, respectively. The enzyme hydrolyzed only single-stranded RNA with a mode of action that was endonucleolytic. The vacuolar ribonuclease had no requirement for divalent metal ions, and did not exhibit phosphomonoesterase (EC 3.1.3.1; EC 3.1.3.2) and phosphodiesterase (EC 3.1.15.1; EC 3.1.16.1) activity. The specificity of the enzyme has been studied by using homopolyribonucleotides as substrates. The end-products obtained were the respective nucleoside 2':3'-cyclic monophosphates and, to minor extents, the corresponding nucleoside 3'(2')-monophosphates. According to these observations, the vacuolar ribonuclease from tomato can be classified as ribonuclease I (EC 3.1.27.1).
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PMID:Ribonuclease in plant vacuoles: purification and molecular properties of the enzyme from cultured tomato cells. 2422 89

A method for the purification of a ribonuclease from potato tubers is described. The preparation was free from deoxyribonuclease and phosphodiesterase activities and possessed only slight phosphomonoesterase activity. Specific antibodies against the ribonuclease preparation were raised in rabbits. Two precipitin arcs were observed on Ouchterlony plates and three by the use of immunoelectrophoresis suggesting that the preparation contained three antigens. Development of one of the arcs on the diffusion plates could be prevented by prior absorption of the RNase preparation with an antiserum specific for phosphomonoesterase from potato tubers. Two of the arcs developing upon immunoelectrophoresis, one of which had low electrophoretic mobility and the other which migrated to the anode, corresponded in position to that of ribonuclease fractionated by agar gel electrophoresis. The remaining arc corresponded to the position of that arising when the RNase antigen was cross-reacted with specific antibodies against phosphomonoesterase from potato tubers. It was concluded that the anti-acid RNase antiserum may be useful for the immunochemical assay of RNase protein when used in conjunction with an anti-phosphomonoesterase antiserum and it was used for this purpose with homogenates derived from damaged and undamaged tuber tissue cv. Majestic. The observations suggested that RNase protein did not parallel the increase in ribonuclease activity following tissue damage and it was concluded that the enhanced RNase activity following mechanical damage may be due to activation of the pre-formed enzyme.
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PMID:Purification of a ribonuclease from potato tubers and its use as an antigen in the immunochemical assay of this protein following tuber damage. 2448 76


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