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)

We have investigated the effect of specific antisense oligonucleotides on both exogenous and endogenous mRNAs in Xenopus oocytes and eggs. Injection of 19- or 20-mers complementary to 70-kd heat shock protein, histone H4 and vegetally localized Veg 1 coding sequences causes rapid cleavage and degradation of up to 96% of the target transcripts present in stage VI oocytes. Nuclear and cytoplasmic transcripts appear to be equally accessible to cytoplasmically injected oligonucleotide and efficient cleavage also occurs in mature oocytes and unfertilized eggs. The residual intact mRNA appears to be completely inaccessible, resisting cleavage by further addition of oligonucleotide. We confirm that antisense oligonucleotides appear to act specifically in vivo, as previously reported in vitro, by directing RNase H cleavage and destabilization of their complementary mRNA.
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PMID:Antisense oligonucleotide-directed cleavage of mRNA in Xenopus oocytes and eggs. 245 30

Hepatitis B viruses replicate through reverse transcription of an RNA intermediate, the pregenomic RNA (pgRNA). Replication is initiated de novo and requires formation of a ribonucleoprotein complex comprising the viral reverse transcriptase (P protein), an RNA stem-loop structure (epsilon) on the pgRNA, and cellular proteins, including the heat shock protein Hsp90, the cochaperone p23, and additional, as yet unknown, factors. Functional complexes catalyze the synthesis of a short DNA primer that is templated by epsilon and covalently linked to the terminal protein (TP) domain of P protein. Currently, the only system for generating such complexes in the test tube is in vitro translation of duck hepatitis B virus (DHBV) P protein in rabbit reticulocyte lysate (RRL), which also provides the necessary factors. However, its limited translation capacity precludes a closer analysis of the complex. To overcome this restriction we sought to produce larger amounts of DHBV P protein by expression in Escherichia coli, followed by complex reconstitution in RRL. Because previous attempts to generate full-length P protein in bacteria have failed we investigated whether separate expression of the TP and reverse transcriptase-RNase H (RT-RH) domains would allow higher yields and whether these domains could trans complement each other. Indeed, TP and, after minor C-terminal modifications, also RT-RH could be expressed in substantial amounts, and when added to RRL, they were capable of epsilon-dependent DNA primer synthesis, demonstrating posttranslational activation. This reconstitution system should pave the way for a detailed understanding of the unique hepadnaviral replication initiation mechanism.
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PMID:Reconstitution of a functional duck hepatitis B virus replication initiation complex from separate reverse transcriptase domains expressed in Escherichia coli. 1146 13