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Self-association of poly(A)-specific ribonuclease (PARN) triggered by the R3H domain

Guang-Jun He1, Yong-Bin Yan2

  • 1State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.

Biochimica Et Biophysica Acta
|September 21, 2014
PubMed

Insights

Poly(A)-specific ribonuclease (PARN), a deadenylase, self-associates into higher-order oligomers. This oligomerization, triggered by the R3H domain, enhances catalytic activity in truncated forms, suggesting a regulatory mechanism for deadenylase function.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Enzymology

Background:

  • Poly(A)-specific ribonuclease (PARN) is a key deadenylase enzyme regulating mRNA stability and cellular processes.
  • PARN typically exists as a dimer in solution and possesses distinct RNA-binding domains (nuclease, R3H, RRM) and a C-terminal domain.

Purpose of the Study:

  • To investigate the self-association behavior of PARN beyond its dimeric state.
  • To elucidate the role of specific domains in PARN oligomerization and its impact on enzymatic activity.

Main Methods:

  • In vitro and in vivo assays to detect PARN self-association into tetramers and higher-order oligomers.
  • Site-directed mutagenesis and spectroscopic analysis (Trp219 fluorescence) to identify domains involved in oligomerization.
  • Enzymatic assays using full-length and truncated PARN variants to assess catalytic activity and processivity.

Main Results:

  • PARN self-associates into tetrameric and higher-order oligomeric structures in vitro and within living cells.
  • The R3H domain is critical for initiating PARN oligomerization, causing conformational changes.
  • While full-length PARN activity is unaffected, tetramerization significantly boosts the catalytic activity and processivity of PARN lacking RRM and C-terminal domains.

Conclusions:

  • PARN self-association is a novel regulatory mechanism controlling its deadenylase activity.
  • Oligomerization may facilitate PARN's concentration at target mRNAs, enabling precise regulation of mRNA decay.
  • The RRM and C-terminal domains modulate the stability of the tetrameric PARN complex.
Keywords:
DeadenylationOligomerizationPoly(A)-specific ribonuclease (PARN)ProcessivityRestricted diffusionmRNA decay

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