2po1
From Proteopedia
Crystal structure of the P. abyssi exosome RNase PH ring complexed with a single stranded 10-mer poly(A) RNA
Overview
Initially identified in yeast, the exosome has emerged as a central component of the RNA maturation and degradation machinery both in Archaea and eukaryotes. Here we describe a series of high-resolution structures of the RNase PH ring from the Pyrococcus abyssi exosome, one of them containing three 10-mer RNA strands within the exosome catalytic chamber, and report additional nucleotide interactions involving positions N5 and N7. Residues from all three Rrp41-Rrp42 heterodimers interact with a single RNA molecule, providing evidence for the functional relevance of exosome ring-like assembly in RNA processivity. Furthermore, an ADP-bound structure showed a rearrangement of nucleotide interactions at site N1, suggesting a rationale for the elimination of nucleoside diphosphate after catalysis. In combination with RNA degradation assays performed with mutants of key amino acid residues, the structural data presented here provide support for a model of exosome-mediated RNA degradation that integrates the events involving catalytic cleavage, product elimination, and RNA translocation. Finally, comparisons between the archaeal and human exosome structures provide a possible explanation for the eukaryotic exosome inability to catalyze phosphate-dependent RNA degradation.
About this Structure
2PO1 is a Protein complex structure of sequences from Pyrococcus abyssi. Full crystallographic information is available from OCA.
Reference
Insights into the mechanism of progressive RNA degradation by the archaeal exosome., Navarro MV, Oliveira CC, Zanchin NI, Guimaraes BG, J Biol Chem. 2008 May 16;283(20):14120-31. Epub 2008 Mar 19. PMID:18353775 Page seeded by OCA on Wed May 28 09:32:00 2008
