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Polypeptides from the myxomycete Physarum polycephalum interacting in vitro with microtubules

C Albertini1, H Akhavan-Niaki, M Wright

  • 1Laboratoire de Pharmacologie et de Toxicologie fondamentales, Centre National de la Recherche Scientifique, Toulouse, France.

Cell Motility and the Cytoskeleton
|January 1, 1990
PubMed

Insights

Physarum polycephalum microtubule-interacting proteins were identified and characterized. A 125 kDa protein was found to be heat-stable and phosphorylated during specific cell cycle phases.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Microtubule-interacting proteins are crucial for cellular functions.
  • Research on these proteins has primarily focused on higher eukaryotes.
  • The lower eukaryote Physarum polycephalum offers a unique model for studying microtubule dynamics.

Purpose of the Study:

  • To identify and characterize microtubule-binding proteins in Physarum polycephalum.
  • To investigate the cross-reactivity and stability of these proteins with mammalian microtubules.
  • To examine the cell cycle-dependent phosphorylation of a specific microtubule-interacting protein.

Main Methods:

  • Affinity purification of microtubule-binding polypeptides from Physarum amoebal crude extracts.
  • Assessment of binding specificity to both amoebal and mammalian microtubules.
  • Heat stability assays and analysis of functional properties of purified fractions.
  • Phosphorylation analysis of the 125 kDa polypeptide during synchronous cell cycles.

Main Results:

  • At least six distinct polypeptides in Physarum extracts specifically bind to amoebal microtubules.
  • These Physarum proteins also bind to mammalian microtubules, indicating conserved interactions.
  • Two polypeptides (125 and 235 kDa) exhibit significant heat stability.
  • A heat-soluble 125 kDa polypeptide fraction shows functional properties.
  • The 125 kDa polypeptide is phosphorylated during late S/early G2 and late G2/prophase stages of the cell cycle.

Conclusions:

  • Physarum polycephalum possesses conserved microtubule-interacting proteins with potential cross-reactivity to mammalian systems.
  • The 125 kDa microtubule-binding protein is a heat-stable, cell cycle-regulated phosphoprotein.
  • These findings provide insights into microtubule regulation in a lower eukaryote model.

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