Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.4 (RNase H)
 2,751 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A retrotransposon named Lian-Aa1 was discovered in an intron of an AaHR3-1 gene of the yellow fever mosquito, Aedes aegypti. This retrotransposon contained a long open reading frame with 1,219 amino acids that included endonuclease, reverse transcriptase, and RNase H domains. It was shown that in the Rock strain of Ae. aegypti, there were up to 1,380 copies of Lian elements, equivalent to 0.8% of the entire genome. Five additional copies of Lian elements were isolated, mapped by restriction digestion, and partially sequenced. The 5' and 3' ends of the Lian family were determined by comparing the terminal sequences of the six copies and were subsequently confirmed by the identification of putative target duplications flanking Lian-Aa1 and Lian-Aa2. The Lian family is likely a novel family of non-long-terminal-repeat (non-LTR) retrotransposons that terminate in a repeat of (CTGA-TAC)2. On average, the six copies of Lian elements showed only 0.6% sequence divergence at the nucleotide level in both a 735-bp region at the 5' end and a 1,124-bp coding region. Genomic Southern blots also revealed a very high degree of similarity among hundreds of Lian elements, suggesting very recent activity of Lian. Furthermore, all six analyzed Lian elements were closely associated with one or more different families of repetitive elements. It is possible that these associations could reflect the complex relationship between Lian elements and the rest of the Ae. aegypti genome. Phylogenetic analyses based on the reverse transcriptase, domains of 36 non-LTR retrotransposons including Lian-Aa1 identified five major subgroups that were supported by bootstrap replications. In contrast to the majority of non-LTR retrotransposons, Lian-Aa1 has an RNase H domain that is similar to a few other non-LTR retrotransposons and some retroviruses, which is consistent with the previously proposed independent assortment of different domains during the evolution of retroelements.
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PMID:Structural, genomic, and phylogenetic analysis of Lian, a novel family of non-LTR retrotransposons in the yellow fever mosquito, Aedes aegypti. 965 85

We have used NMR and CD spectroscopy to study the conformations of modified oligonucleotides (locked nucleic acid, LNA) containing a conformationally restricted nucleotide (T(L)) with a 2'-O,4'-C-methylene bridge. We have investigated two LNA:RNA duplexes, d(CTGAT(L)ATGC):r(GCAUAUCAG) and d(CT(L)GAT(L)AT(L)GC):r(GCAUAUCAG), along with the unmodified DNA:RNA reference duplex. Increases in the melting temperatures of +9.6 degrees C and +8.1 degrees C per modification relative to the unmodified duplex were observed for these two LNA:RNA sequences. The three duplexes all adopt right-handed helix conformations and form normal Watson-Crick base pairs with all the bases in the anti conformation. Sugar conformations were determined from measurements of scalar coupling constants in the sugar rings and distance information derived from 1H-1H NOE measurements; all the sugars in the RNA strands of the three duplexes adopt an N-type conformation (A-type structure), whereas the sugars in the DNA strands change from an equilibrium between S- and N-type conformations in the unmodified duplex towards more of the N-type conformation when modified nucleotides are introduced. The presence of three modified T(L) nucleotides induces drastic conformational shifts of the remaining unmodified nucleotides of the DNA strand, changing all the sugar conformations except those of the terminal sugars to the N type. The CD spectra of the three duplexes confirm the structural changes described above. On the basis of the results reported herein, we suggest that the observed conformational changes can be used to tune LNA:RNA duplexes into substrates for RNase H: Partly modified LNA:RNA duplexes may adopt a duplex structure between the standard A and B types, thereby making the RNA strand amenable to RNase H-mediated degradation.
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PMID:Structural studies of LNA:RNA duplexes by NMR: conformations and implications for RNase H activity. 1098 17

Sugar signalling cascades are important components of regulatory networks in cells. Compared with the situation in bacteria, yeast and animals, participants of the sugar signalling pathways in plants are poorly understood. Several genes involved in starch synthesis are known to be sugar inducible, although the signal transduction pathways remain undisclosed. We reported recently the isolation of SUSIBA2, a transcription factor involved in sugar-mediated regulation of starch synthesis. Here, we used antisense oligodeoxynucleotide (ODN) inhibition, a powerful approach in medical sciences, to block the effects of SUSIBA2 in sugar-treated barley leaves. The uptake and intracellular trafficking of an 18-mer susiba2 antisense ODN in leaves were followed by confocal microscopy. Administration of the antisense ODN to the leaves impeded susiba2 expression by RNase H activation. This dramatically diminished the ectopic expression of the iso1 and sbeIIb genes and resulted in altered starch synthesis. This study illustrates the successful exploitation of the antisense ODN technology in plant biology, e.g. as a rapid antecedent to time-consuming transgenic studies, and identifies SUSIBA2 as a transcriptional activator in plant sugar signalling. Based on our findings, we propose a model for sugar-signalling control of starch synthesis.
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PMID:Antisense oligodeoxynucleotide inhibition as a potent strategy in plant biology: identification of SUSIBA2 as a transcriptional activator in plant sugar signalling. 1616 1