title: Mechanisms of RNA recruitment by the exosome.
abstract: Exosome-like protein complexes are essential 3'−>5' ribonucleases involved in processing and degradation of many RNAs. They are conserved in the three domains of life and share a common architecture comprised of a ring-like core structure organized around a central channel. RNA degradation by bacterial and archaeal exosome-like complexes requires threading through this single-stranded RNA specific channel to reach the phosphorolytic active sites buried deep within the barrel-shaped complex. In contrast most eukaryotic exosomes appear to have lost phosphorolytic activity and instead rely on hydrolytic RNases for catalytic activity raising the question of the degree of conservation of RNA recruitment mechanisms between prokaryotic and eukaryotic complexes. Recent single particle electron microscopy reconstructions of apo and RNA bound yeast exosomes provide the first direct structural evidence for a channeling mechanism by a eukaryotic exosome suggesting that this mechanism is conserved between all exosome-like complexes.
authors.affiliation: Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London, UK.
authors.forename: Hélène
authors.initials: H
authors.lastname: Malet
authors.forename: Esben
authors.initials: E
authors.lastname: Lorentzen
mesh_terms: D004722:Endoribonucleases / Q000378:metabolism; D005095:Exoribonucleases / Q000378:metabolism; D055354:Exosomes / Q000378:metabolism*; D008854:Microscopy, Electron; D008958:Models, Molecular; D011487:Protein Conformation; D012313:RNA / Q000378:metabolism*; D015003:Yeasts / Q000378:metabolism
chemical_list: D012313:RNA; D004722:Endoribonucleases; D005095:Exoribonucleases