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Mdm20 protein functions with Nat3 protein to acetylate Tpm1 protein and regulate tropomyosin-actin interactions in

Jason M Singer1, Janet M Shaw

  • 1Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.

Proceedings of the National Academy of Sciences of the United States of America
|June 17, 2003
PubMed

Insights

Mdm20 protein is crucial for stabilizing actin cables in yeast by enabling N-terminal acetylation of tropomyosin Tpm1p. This modification by the NatB complex ensures proper Tpm1p function and actin cable stability.

Area of Science:

  • Cell biology
  • Protein biochemistry
  • Cytoskeletal dynamics

Background:

  • The Mdm20 protein (Mdm20p) is essential for actin filament and cable formation in budding yeast.
  • Mdm20p's precise role in actin cable stability, despite not being a structural component, remained unclear.

Purpose of the Study:

  • To elucidate the function of Mdm20p in the stabilization of actin filaments and cables.
  • To investigate the molecular mechanism by which Mdm20p influences tropomyosin (Tpm1p) activity.

Main Methods:

  • Genetic analysis in budding yeast.
  • Biochemical assays to assess protein acetylation and F-actin binding.
  • Co-purification studies to identify interacting proteins.

Main Results:

  • Cells lacking Mdm20p exhibit a failure in N-terminal acetylation of Tpm1p.
  • Unacetylated Tpm1p shows significantly reduced F-actin binding activity compared to the acetylated form.
  • Mdm20p was found to function cooperatively with Nat3p, the catalytic subunit of the NatB acetyltransferase complex.

Conclusions:

  • Mdm20p-dependent N-terminal acetylation of Tpm1p by the NatB complex is essential for Tpm1p's association with and stabilization of actin filaments and cables.
  • This acetylation process is a key regulatory mechanism for cytoskeletal organization and function in yeast.

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