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)

Semiempirical potential energy calculations have been carried out to locate possible binding sites for purine nucleoside phosphates at the RNase S active center. The nucleobase of adenosine or 8-oxoadenosine was shown to be accommodated at the pyrimidine binding site of the enzyme provided the nucleoside must be "syn". The mutual orientation of 8-oxoadenosine carbonyl group and NH-group of Thr-45 suggests a formation of a corresponding hydrogen bond in the enzyme--nucleotide complex. The formation of the hydrogen bond was postulated earlier to be essential for specific recognition of the substrate by RNase. The results obtained are in good agreement with the postulate. The "leaving group" binding site at the RNase S active center was found to be nonspecific toward conformation (syn-anti) of purine nucleotides studied. In addition, optimal conformation of dinucleosidemonophosphate bound to the enzyme active site was estimated for Pyr-P-Pur substrates.
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PMID:[Theoretical conformational analysis of noncovalent complexes of purine nucleotides with ribonuclease]. 712 59

The quantitative aspect of the electrochemical detection method to detect 8-oxo-7,8-dihydroguanine (8-oxoGua) has been improved by using an internal standard. In addition, emphasis was placed on the reduction of artifactual oxidation of DNA during isolation and hydrolysis. Nuclear DNA was isolated from rat organs and purified on an anion-exchange column following treatment with proteinase K and RNase. DNA hydrolysis to nucleobases or nucleosides was performed using either formic acid treatment or enzymatic digestion, respectively. The levels of either 8-oxoGua or 8-hydroxy-7,8-dihydro-2'-deoxyguanosine were comparable. For accurate quantification, 2,6-diamino-8-oxopurine [(NH2)2-OH-Pur], added prior to hydrolysis, was used as an internal standard for the high-performance liquid chromatography with electrochemical detection assay. The baseline level of 8-oxoGua in DNA of Sprague-Dawley rats was estimated to be 2 to 5 8-oxoGua residues per 10(6) DNA bases, with slight differences depending on the tissue origin. In agreement with the results of previous observations, the level of the oxidized base in the kidney of animal treated with iron complexed to nitrilotriacetic acid (Fe-NTA) (15 mg/kg) was three- to fourfold higher than that of untreated rats or animals treated with a saline solution, while there was no change in 8-oxoGua levels in the liver and colon of these treated animals.
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PMID:Detection of 8-oxoguanine in cellular DNA using 2,6-diamino-8-oxopurine as an internal standard for high-performance liquid chromatography with electrochemical detection. 964 49

A complex between the Tat protein, encoded by human immunodeficiency virus type 1 (HIV-1), and the cellular protein, Puralpha, has been implicated in activation of the late promoter of JC virus (JCV) and in enhancement of JCV DNA replication. JCV is the causative agent of progressive multifocal leukoencephalopathy (PML), an acquired immunodeficiency syndrome (AIDS) opportunistic infection of the brain. Puralpha also binds the HIV-1 TAR RNA element and activates HIV-1 transcription, suggesting a role for RNA binding in the action of this protein. Using immunoelectron microscopy, we find that in human glial cells expressing both proteins, Tat and Puralpha are colocalized in extranucleolar chromatin structural elements. The colocalized Puralpha and Tat are nearly exclusively nuclear, although individual proteins can be seen in both nucleus and cytoplasm, suggesting a preferential tropism of the complex for the nucleus. Analysis of the interaction between purified proteins indicates that the Tat-Puralpha interaction is strongly enhanced by the presence of RNA. Tat amino acids from 37-48 are essential for Tat binding. Residues 49-72, including the TAR RNA-binding domain, are critical for binding to Puralpha, while Cys(22), in the Tat transactivation domain, is responsible for an important global effect. Puralpha repeat II domains are involved in the interaction, and a polypeptide based on one such sequence inhibits binding. After RNase treatment of Puralpha enhancement of Tat binding can be partially restored by addition of a single-stranded JCV DNA PUR element, to which Tat does not bind. The results indicate that the Tat-Puralpha interaction is direct, rather than through an RNA link, and that RNA binding configures Puralpha for optimal interaction with Tat.
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PMID:Interaction of HIV-1 Tat with Puralpha in nuclei of human glial cells: characterization of RNA-mediated protein-protein binding. 1067 17

Pur alpha is an abundant protein in the brain and binds to a (GGN)n sequence, PUR element. It has been shown that Pur alpha not only interacts with single stranded DNA and RNA, but also with various proteins. In the present study, we tried to search for Pur alpha-binding proteins (PurBPs) in mouse brain by the overlay assay with GST-Pur alpha as a ligand. Three PurBPs of 35, 38 and 40 kDa were found mostly in the nuclear extract (N.Ext.) and they were not detected by the pretreatment of N.Ext. with trypsin, but not with RNase or DNase. The three PurBPs disappeared by the addition of ssCRE (single stranded cAMP response element) containing a PUR element, but not by DeltaGGN ssCRE (deletion of the PUR element from the ssCRE). The PurBPs were abundantly expressed in the brain as Pur alpha. We also determined a region in Pur alpha which is required for the association with the PurBPs by using deletion mutants of Pur alpha. These biochemical properties of the PurBPs are different from the reported nuclear Pur alpha-binding proteins such as Sp1 and pRb.
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PMID:Characterization of novel Pur alpha-binding proteins in mouse brain. 1523 19

RNA transport is an important and fundamental event for local protein synthesis, especially in neurons. RNA is transported as large granules, but little is known about them. Here, we isolated a large RNase-sensitive granule (size: 1000S approximately) as a binding partner of conventional kinesin (KIF5). We identified a total of 42 proteins with mRNAs for CaMKIIalpha and Arc in the granule. Seventeen of the proteins (hnRNP-U, Pur alpha and beta, PSF, DDX1, DDX3, SYNCRIP, TLS, NonO, HSPC117, ALY, CGI-99, staufen, three FMRPs, and EF-1alpha) were extensively investigated, including their classification, binding combinations, and necessity for the "transport" of RNA. These proteins and the mRNAs were colocalized to the kinesin-associated granules in dendrites. The granules moved bidirectionally, and the distally directed movement was enhanced by the overexpression of KIF5 and reduced by its functional blockage. Thus, kinesin transports RNA via this granule in dendrites coordinately with opposite motors, such as dynein.
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PMID:Kinesin transports RNA: isolation and characterization of an RNA-transporting granule. 1531 43