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SMG7 is a 14-3-3-like adaptor in the nonsense-mediated mRNA decay pathway

Noemi Fukuhara1, Judith Ebert, Leonie Unterholzner

  • 1European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany.

Molecular Cell
|February 22, 2005
PubMed

Insights

SMG7 protein structure reveals a 14-3-3-like domain crucial for nonsense-mediated mRNA decay (NMD). This finding clarifies SMG7

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Nonsense-mediated mRNA decay (NMD) regulates gene expression by degrading aberrant mRNAs.
  • Phosphorylation of UPF1 is a key regulatory step in NMD.
  • SMG5, SMG6, and SMG7 proteins dephosphorylate UPF1.

Purpose of the Study:

  • To determine the crystal structure of the N-terminal domain of SMG7.
  • To elucidate the mechanism by which SMG7 interacts with UPF1.
  • To understand the role of SMG7 in NMD.

Main Methods:

  • X-ray crystallography to determine SMG7 structure.
  • In vitro binding assays to assess UPF1-SMG7 interaction.
  • In vivo studies to observe UPF1 recruitment to decay foci.

Main Results:

  • The crystal structure of SMG7's N-terminal domain revealed a 14-3-3-like domain.
  • Conserved residues in SMG7 mimic 14-3-3 phosphoserine-binding sites.
  • Mutating these residues disrupted UPF1 binding in vitro and in vivo.

Conclusions:

  • SMG7 functions as an adaptor protein, linking phosphorylated UPF1 to mRNA degradation machinery.
  • The 14-3-3-like domain is critical for SMG7's role in NMD.
  • Homologous domains in SMG5, SMG6, and potentially human Est1 suggest conserved regulatory roles in mRNA decay and telomere biology.

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