Abstract
The specialized ribonuclease Dicer initiates RNA interference by cleaving double-stranded RNA (dsRNA) substrates into small fragments about 25 nucleotides in length. In the crystal structure of an intact Dicer enzyme, the PAZ domain, a module that binds the end of dsRNA, is separated from the two catalytic ribonuclease III (RNase III) domains by a flat, positively charged surface. The 65 angstrom distance between the PAZ and RNase III domains matches the length spanned by 25 base pairs of RNA. Thus, Dicer itself is a molecular ruler that recognizes dsRNA and cleaves a specified distance from the helical end.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Conserved Sequence
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Crystallography, X-Ray
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Giardia lamblia / enzymology
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Humans
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Lanthanoid Series Elements / metabolism
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Models, Molecular
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Molecular Sequence Data
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Protein Structure, Tertiary
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RNA Interference
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RNA, Double-Stranded / metabolism*
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RNA, Protozoan / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Ribonuclease III / chemistry*
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Ribonuclease III / metabolism
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Schizosaccharomyces / genetics
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Structure-Activity Relationship
Substances
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Lanthanoid Series Elements
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RNA, Double-Stranded
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RNA, Protozoan
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Recombinant Fusion Proteins
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Dicer protein, Giardia intestinalis
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Ribonuclease III