Insights into the mechanism of progressive RNA degradation by the archaeal exosome

Almost all RNA species produced by a cell undergo several post-transcriptional processing reactions to produce functional RNA molecules. The exosome complex is a central component of the RNA maturation and degradation machinery both in archaea and in eukaryotes. In this work, a series of crystallographic structures of the RNase PH ring from Pyrococcus abyssi exosome in combination with RNA degradation assays performed with mutants of key amino acid residues, allowed to propose a model of exosome-mediated RNA degradation which integrates the events involving catalytic cleavage, product elimination and RNA translocation. (author)