1w9h

From Proteopedia

Revision as of 08:20, 3 February 2008

THE STRUCTURE OF A PIWI PROTEIN FROM ARCHAEOGLOBUS FULGIDUS.

Overview

RNA silencing regulates gene expression through mRNA degradation, translation repression and chromatin remodelling. The fundamental engines, of RNA silencing are RISC and RITS complexes, whose common components are, 21-25 nt RNA and an Argonaute protein containing a PIWI domain of unknown, function. The crystal structure of an archaeal Piwi protein (AfPiwi) is, organised into two domains, one resembling the sugar-binding portion of, the lac repressor and another with similarity to RNase H. Invariant, residues and a coordinated metal ion lie in a pocket that surrounds the, conserved C-terminus of the protein, defining a key functional region in, the PIWI domain. Furthermore, two Asp residues, conserved in the majority, of Argonaute sequences, align spatially with the catalytic Asp residues of, RNase H-like catalytic sites, suggesting that in eukaryotic Argonaute, proteins the RNase H-like domain may possess nuclease activity. The, conserved region around the C-terminus of the PIWI domain, which is, required for small interfering RNA (siRNA) binding to AfPiwi, may function, as the receptor site for the obligatory 5' phosphate of siRNAs, thereby, specifying the cleavage position of the target mRNA.

About this Structure

1W9H is a Single protein structure of sequence from Archaeoglobus fulgidus with , and as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

Crystal structure of a PIWI protein suggests mechanisms for siRNA recognition and slicer activity., Parker JS, Roe SM, Barford D, EMBO J. 2004 Dec 8;23(24):4727-37. Epub 2004 Nov 25. PMID:15565169

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