2ba0
Archaeal exosome core
OverviewOverview
Exosomes emerge as central 3'-->5' RNA processing and degradation machineries in eukaryotes and archaea. We determined crystal structures of two 230 kDa nine subunit archaeal exosome isoforms. Both exosome isoforms contain a hexameric ring of RNase phosphorolytic (PH) domain subunits with a central chamber. Tungstate soaks identified three phosphorolytic active sites in this processing chamber. A trimer of Csl4 or Rrp4 subunits forms a multidomain macromolecular interaction surface on the RNase-PH domain ring with central S1 domains and peripheral KH and zinc-ribbon domains. Structural and mutational analyses suggest that the S1 domains and a subsequent neck in the RNase-PH domain ring form an RNA entry pore to the processing chamber that only allows access of unstructured RNA. This structural framework can mechanistically unify observed features of exosomes, including processive degradation of unstructured RNA, the requirement for regulatory factors to degrade structured RNA, and left-over tails in rRNA trimming.
About this StructureAbout this Structure
2BA0 is a Protein complex structure of sequences from Archaeoglobus fulgidus. Full crystallographic information is available from OCA.
ReferenceReference
Structural framework for the mechanism of archaeal exosomes in RNA processing., Buttner K, Wenig K, Hopfner KP, Mol Cell. 2005 Nov 11;20(3):461-71. PMID:16285927 Page seeded by OCA on Sat May 3 20:02:00 2008