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Profiles of Physarum Microplasmodial Phosphatase Activity Crucial to Cytoplasmic Streaming and Spherule Formation

Chisa Y Okada1,2, Akio Nakamura3, Kyoko Ogawa4

  • 1Support Center for Medical Research and Education, Tokai University, Isehara, Kanagawa, 259-1193, Japan. cokada@tokai-u.jp.

Cell Biochemistry and Biophysics
|September 29, 2019
PubMed

Insights

Physarum microplasmodial phosphatase (PPH) activity increases, leading to decreased cytoplasmic streaming and spherule formation during dark starvation. This suggests PPH plays a key role in Physarum microplasmodia

Area of Science:

  • Biochemistry
  • Cell Biology
  • Mycology

Background:

  • Physarum microplasmodia exhibit cytoplasmic streaming essential for nutrient transport.
  • Dark starvation (DS) induces spherule formation, a quiescent stage in Physarum.
  • The molecular mechanisms regulating this transition are not fully understood.

Purpose of the Study:

  • To investigate the role of Physarum microplasmodial phosphatase (PPH) in spherule formation during dark starvation.
  • To characterize PPH activity towards the phosphorylated light chain of Physarum myosin II (PLCM).
  • To correlate PPH expression and activity with changes in cytoplasmic streaming velocity.

Main Methods:

  • Cloning of full-length PPH cDNA using PCR based on N-terminal amino acid sequence.
  • Measurement of PPH activity at pH 7.6.
  • Monitoring cytoplasmic streaming velocity.
  • Analysis of PPH expression and accumulation during dark starvation.
  • Production of recombinant PPH using a wheat germ cell-free expression system.

Main Results:

  • A rapid increase in PPH activity towards PLCM and a decrease in cytoplasmic streaming velocity were observed preceding spherule formation.
  • PPH expression and accumulation during DS correlated with spherule formation.
  • Recombinant PPH produced via cell-free expression showed phosphatase activity towards PLCM.

Conclusions:

  • PPH activity is upregulated during dark starvation in Physarum microplasmodia.
  • Increased PPH activity is linked to the cessation of cytoplasmic streaming.
  • PPH is implicated in the transition to spherule formation in Physarum microplasmodia.
Keywords:
Cytoplasmic streamingMicroplasmodiaMyosin IIPhysarum polycephalumSpherule formationcDNA cloning

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