2A1S | pdb_00002a1s

Structural insight into poly(A) binding and catalytic mechanism of human PARN

(2005) EMBO J&nbsp24: 4082-4093

• PubMed:&nbsp16281054&nbspSearch on PubMedSearch on PubMed Central
• DOI:&nbsphttps://doi.org/10.1038/sj.emboj.7600869
• Primary Citation of Related Structures: &nbsp
  2A1R, 2A1S


• PubMed Abstract:&nbsp
  

  Poly(A)-specific ribonuclease (PARN) is a processive, poly(A)-specific 3' exoribonuclease. The crystal structure of C-terminal truncated human PARN determined in two states (free and RNA-bound forms) reveals that PARNn is folded into two domains, an R3H domain and a nuclease domain similar to those of Pop2p and epsilon186. The high similarity of the active site structures of PARNn and epsilon186 suggests that they may have a similar catalytic mechanism. PARNn forms a tight homodimer, with the R3H domain of one subunit partially enclosing the active site of the other subunit and poly(A) bound in a deep cavity of its nuclease domain in a sequence-nonspecific manner. The R3H domain and, possibly, the cap-binding domain are involved in poly(A) binding but these domains alone do not appear to contribute to poly(A) specificity. Mutations disrupting dimerization abolish both the enzymatic and RNA-binding activities, suggesting that the PARN dimer is a structural and functional unit. The cap-binding domain may act in concert with the R3H domain to amplify the processivity of PARN.

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Organizational Affiliation:&nbsp

Laboratory of Macromolecular Structure, Institute of Molecular and Cell Biology, Proteos, Singapore.