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| {{STRUCTURE_1ytu| PDB=1ytu | SCENE= }} | | {{STRUCTURE_1ytu| PDB=1ytu | SCENE= }} |
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| '''Structural basis for 5'-end-specific recognition of the guide RNA strand by the A. fulgidus PIWI protein'''
| | ===Structural basis for 5'-end-specific recognition of the guide RNA strand by the A. fulgidus PIWI protein=== |
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| ==Overview==
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| RNA interference (RNAi) is a conserved sequence-specific gene regulatory mechanism mediated by the RNA-induced silencing complex (RISC), which is composed of a single-stranded guide RNA and an Argonaute protein. The PIWI domain, a highly conserved motif within Argonaute, has been shown to adopt an RNase H fold critical for the endonuclease cleavage activity of RISC. Here we report the crystal structure of Archaeoglobus fulgidus Piwi protein bound to double-stranded RNA, thereby identifying the binding pocket for guide-strand 5'-end recognition and providing insight into guide-strand-mediated messenger RNA target recognition. The phosphorylated 5' end of the guide RNA is anchored within a highly conserved basic pocket, supplemented by the carboxy-terminal carboxylate and a bound divalent cation. The first nucleotide from the 5' end of the guide RNA is unpaired and stacks over a conserved tyrosine residue, whereas successive nucleotides form a four-base-pair RNA duplex. Mutation of the corresponding amino acids that contact the 5' phosphate in human Ago2 resulted in attenuated mRNA cleavage activity. Our structure of the Piwi-RNA complex, and that determined elsewhere, provide direct support for the 5' region of the guide RNA serving as a nucleation site for pairing with target mRNA and for a fixed distance separating the RISC-mediated mRNA cleavage site from the anchored 5' end of the guide RNA.
| | The line below this paragraph, {{ABSTRACT_PUBMED_15800629}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 15800629 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_15800629}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Protein-rna complex]] | | [[Category: Protein-rna complex]] |
| [[Category: Rna duplex]] | | [[Category: Rna duplex]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 16:46:57 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 17:02:42 2008'' |
