Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.3 (RNase III)
 1,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Control of RNA turnover is a major, but poorly understood, aspect of gene regulation. In multicellular organisms, progress toward dissecting RNA turnover pathways has been made by defining some cis-acting sequences that function as either regulatory or cleavage targets (J. G. Belasco and G. Brawerman, Control of Messenger RNA Stability, 1993). However, the identification of genes encoding proteins that regulate or cleave target RNAs has been elusive (C. A. Beelman and R. Parker, Cell 81:79-183, 1995); this gap in knowledge has made it difficult to identify additional components of RNA turnover pathways. We have utilized a modified expression cloning strategy to identify a developmentally regulated gene from Drosophila melanogaster that encodes a RNase that we refer to as Clipper (CLP). Significant sequence matches to open reading frames encoding unknown functions identified from the Caenorhabditis elegans and Saccharomyces cerevisiae genome sequencing projects suggest that all three proteins are members of a new protein family conserved from lower eukaryotes to invertebrates. We demonstrate that a member of this new protein family specifically cleaves RNA hairpins and that this activity resides in a region containing five copies of a previously uncharacterized CCCH zinc finger motif. CLP's endoribonucleolytic activity is distinct from that associated with RNase A (P. Blackburn and S. Moore, p. 317-433, in P. D. Boyer, ed., The Enzymes, vol. XV, part B, 1982) and is unrelated to RNase III processing of rRNAs and tRNAs (J. G. Belasco and G. Brawerman, Control of Messenger RNA Stability, 1993, and S. A. Elela, H. Igel, and M. Ares, Cell 85:115-124, 1995). Our results suggest that CLP may function directly in RNA metabolism.
 ...
PMID:Cleavage of RNA hairpins mediated by a developmentally regulated CCCH zinc finger protein. 894 20

Viruses encode silencing suppressor proteins to counteract RNA silencing. Because dsRNA plays a key role in silencing, a general silencing suppressor strategy is dsRNA binding. The p22 suppressor of the plant virus Tomato chlorosis virus (ToCV; genus Crinivirus, family Closteroviridae) has been described as having one of the longest lasting local suppressor activities. However, the mechanism of action of p22 has not been characterized. Here, we show that ToCV p22 binds long dsRNAs in vitro, thus interfering with their processing into small RNAs (sRNAs) by an RNase III-type Dicer homolog enzyme. Additionally, we have studied whether a putative zinc finger motif found in p22 has a role in dsRNA binding and suppressor function. The efficient ability of p22 to suppress RNA silencing, triggered by hairpin transcripts transiently expressed in planta, supports the relationship between its ability to bind dsRNA in vitro and its ability to inhibit RNA silencing in vivo.
...
PMID:The p22 RNA silencing suppressor of the crinivirus Tomato chlorosis virus preferentially binds long dsRNAs preventing them from cleavage. 2662 53