Ski2-like RNA helicase structures

Abstract

Ski2-like RNA helicases are large multidomain proteins involved \rin a variety of RNA processing and degradation events. Recent \rstructures of Mtr4, Ski2 and Brr2 provide our first view of \rthese intricate helicases. Here we review these structures, \rwhich reveal a conserved ring-like architecture that extends \rbeyond the canonical RecA domains to include a winged helix \rand ratchet domain. Comparison of apo- and RNA-bound \rMtr4 structures suggests a role for the winged helix domain \ras a molecular hub that coordinates RNA interacting events \rthroughout the helicase. Unique accessory domains provide \rexpanded diversity and functionality to each Ski2-like family \rmember. A common theme is the integration of Ski2-like \rRNA helicases into larger protein assemblies. We describe the \rcentral role of Mtr4 and Ski2 in formation of complexes that \ractivate RNA decay by the eukaryotic exosome. The current \rstructures provide clues into what promises to be a fascinating \rview of these dynamic assemblies.