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PDBsum entry 2ba0
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RNA binding protein
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PDB id
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2ba0
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Contents |
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218 a.a.
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246 a.a.
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253 a.a.
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References listed in PDB file
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Key reference
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Title
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Structural framework for the mechanism of archaeal exosomes in RNA processing.
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Authors
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K.Büttner,
K.Wenig,
K.P.Hopfner.
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Ref.
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Mol Cell, 2005,
20,
461-471.
[DOI no: ]
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PubMed id
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Abstract
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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.
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Figure 2.
Figure 2. Phosphorolytic Active Sites
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Figure 6.
Figure 6. Proposed Mechanism for Core Exosomes
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The above figures are
reprinted
by permission from Cell Press:
Mol Cell
(2005,
20,
461-471)
copyright 2005.
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