Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Stress-induced phosphorylation of eIF2alpha inhibits global protein synthesis to conserve energy for repair of stress-induced damage. Stress-induced translational arrest is observed in cells expressing a nonphosphorylatable eIF2alpha mutant (S51A), which indicates the existence of an alternative pathway of translational control. In this paper, we show that arsenite, heat shock, or ultraviolet irradiation promotes transfer RNA (tRNA) cleavage and accumulation of tRNA-derived, stress-induced small RNAs (tiRNAs). We show that angiogenin, a secreted ribonuclease, is required for stress-induced production of tiRNAs. Knockdown of angiogenin, but not related ribonucleases, inhibits arsenite-induced tiRNA production and translational arrest. In contrast, knockdown of the angiogenin inhibitor RNH1 enhances tiRNA production and promotes arsenite-induced translational arrest. Moreover, recombinant angiogenin, but not RNase 4 or RNase A, induces tiRNA production and inhibits protein synthesis in the absence of exogenous stress. Finally, transfection of angiogenin-induced tiRNAs promotes phospho-eIF2alpha-independent translational arrest. Our results introduce angiogenin and tiRNAs as components of a phospho-eIF2alpha-independent stress response program.
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PMID:Angiogenin cleaves tRNA and promotes stress-induced translational repression. 1933 86

Lactoferrin (LF) is known as an iron-binding antimicrobial protein present in exocrine secretions such as milk and releases the potent antimicrobial peptide lactoferricin (LFcin) by hydrolysis with pepsin. The antimicrobial activity of LF and LFcin has been studied well; however, their cooperative action with other milk proteins remains to be elucidated. In this study, we identified milk proteins enhancing the antimicrobial activity of bovine LF and LFcin against gram-negative bacteria, gram-positive bacteria, and fungi. As the target fraction, we isolated a minor milk protein fraction around 15 kDa, which was identified as bovine RNase 5 (angiogenin-1), RNase 4, and angiogenin-2 by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. As these proteins are collectively known as the RNase A family, we referred to the target protein fraction as milk RNase of 15 kDa (MR15). The number of colony-forming units of Escherichia coli and other pathogenic microorganisms with the addition of MR15 to LF (MR15:LF ratio=16:1,000) was dramatically lowered than that with LF alone. On the other hand, MR15 itself did not show any reductions in the number of colony-forming units at the concentrations tested. Similarly, the antimicrobial activities of LFcin against various microorganisms were significantly enhanced by the addition of MR15. These results suggest that LF and MR15 may be concomitantly acting antimicrobial agents in milk.
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PMID:Identification of milk proteins enhancing the antimicrobial activity of lactoferrin and lactoferricin. 2376 63

Cytotoxic ribonucleases found in the oocytes and early embryos of frogs with antitumor activity are well-documented. RC-RNase 2, a cytotoxic ribonuclease isolated from oocytes of bullfrog Rana catesbeiana, consists of 105 residues linked with 4 disulfide bridges and belongs to the bovine pancreatic ribonuclease (RNase A) superfamily. Among the RC-RNases, the base preference for RNase 2 is UpG but CpG for RC-RNase 4; while RC-RNase possesses the base specificity of both UpG and CpG. Interestingly, RC-RNase 2 or 4 has much lower catalytic activity but only three-fold less cytotoxicity than RC-RNase. Here, we report the NMR solution structure of rRC-RNase 2, comprising three alpha-helices and two sets of antiparallel beta-sheets. The differences of side-chain conformations of subsite residues among RNase A, RC-RNase, RC-RNase 4 and rRNase 2 are related to their distinct catalytic activities and base preferences. Furthermore, the substrate-related residues in the base specificity among native RC-RNases are derived using the chemical shift perturbation on ligand binding.
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PMID:Solution structure and base specificity of cytotoxic RC-RNase 2 from Rana catesbeiana. 2630 48


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