Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The locations of transfer RNA genes with respect to the restriction endonuclease cleavage map of Euglena gracilis Klebs, strain Z Pringsheim chloroplast DNA have been determined. Purified chloroplast tRNAs were treated with snake venom phosphodiesterase to remove the 3'-CCA terminus, and radioactively labeled by the action of Escherichia coli tRNA nucleotidyltransferase in the presence of [alpha-32P]CTP. Chloroplast DNA was treated individually and with combinations of the enzymes Bal I, Bam HI, Eco RI, Pst I, Pvu II, Sal I, and Xho I. The location of tRNA genes with respect to the cleavage sites for these enzymes was determined by hybridization of the 32P-labeled tRNAs to membrane filter blots of the chloroplast DNA restriction nuclease fragments following gel electrophoresis. The 145-kilobase pair genome was resolved into nine areas of strong tRNA hybridization, separated by areas of weak or no tRNA hybridization. The loci of tRNA genes are within the Eco RI fragments Eco A, B, G, H, I, J', P, Q, and V.
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PMID:Euglena gracilis chloroplast transfer RNA transcription units. I. Physical map of the transfer RNA gene loci. 627 29

Ribosomal RNA (rRNA) is a major component of ribosomes and is fundamental to the process of translation. In bacteria, 16S rRNA is a component of the small ribosomal subunit and plays a critical role in mRNA decoding. rRNA maturation entails the removal of intervening spacer sequences contained within the pre-rRNA transcript by nucleolytic enzymes. Enzymatic activities involved in maturation of the 5'-end of 16S rRNA have been identified, but those involved in 3'-end maturation of 16S rRNA are more enigmatic. Here, we investigate molecular details of 16S rRNA maturation using purified in vivo-formed small subunit (SSU) assembly intermediates (pre-SSUs) from wild-type Escherichia coli that contain precursor 16S rRNA (17S rRNA). Upon incubation of pre-SSUs with E. coli S100 cell extracts or purified enzymes implicated in 16S rRNA processing, the 17S rRNA is processed into additional intermediates and mature 16S rRNA. These results illustrate that exonucleases RNase R, RNase II, PNPase, and RNase PH can process the 3'-end of pre-SSUs in vitro. However, the endonuclease YbeY did not exhibit nucleolytic activity with pre-SSUs under these conditions. Furthermore, these data demonstrate that multiple pathways facilitate 16S rRNA maturation with pre-SSUs in vitro, with the dominant pathways entailing complete processing of the 5'-end of 17S rRNA prior to 3'-end maturation or partial processing of the 5'-end with concomitant processing of the 3'-end. These results reveal the multifaceted nature of SSU biogenesis and suggest that E. coli may be able to escape inactivation of any one enzyme by using an existing complementary pathway.
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PMID:Characterization of 16S rRNA Processing with Pre-30S Subunit Assembly Intermediates from E. coli. 2966 Mar 26

RNA molecules are frequently modified with a terminal 2',3'-cyclic phosphate group as a result of endonuclease cleavage, exonuclease trimming, or de novo synthesis. During pre-transfer RNA (tRNA) and unconventional messenger RNA (mRNA) splicing, 2',3'-cyclic phosphates are substrates of the tRNA ligase complex, and their removal is critical for recycling of tRNAs upon ribosome stalling. We identified the predicted deadenylase angel homolog 2 (ANGEL2) as a human phosphatase that converts 2',3'-cyclic phosphates into 2',3'-OH nucleotides. We analyzed ANGEL2's substrate preference, structure, and reaction mechanism. Perturbing ANGEL2 expression affected the efficiency of pre-tRNA processing, X-box-binding protein 1 (XBP1) mRNA splicing during the unfolded protein response, and tRNA nucleotidyltransferase 1 (TRNT1)-mediated CCA addition onto tRNAs. Our results indicate that ANGEL2 is involved in RNA pathways that rely on the ligation or hydrolysis of 2',3'-cyclic phosphates.
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PMID:ANGEL2 is a member of the CCR4 family of deadenylases with 2',3'-cyclic phosphatase activity. 3273 18