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Mol. Cell. Biol., 12 1996, 6661-6667, Vol 16, No. 12
C Bai and PP Tolias
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.
Copyright © 1996, American Society for Microbiology
Cleavage of RNA hairpins mediated by a developmentally regulated CCCH zinc finger protein
Public Health Research Institute, New York, New York 10016, USA.
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