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Analysis of Translation Initiation During Stress Conditions by Polysome Profiling
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Analysis of Translation Initiation During Stress Conditions by Polysome Profiling

Published on: May 19, 2014

Translational control and the cytoskeleton in Physarum polycephalum

R D Brodeur, W R Jeffery

    Cell Motility and the Cytoskeleton
    |January 1, 1987
    PubMed

    Insights

    During starvation, slime mold Physarum polycephalum shifts protein synthesis components from the cytoskeleton to the soluble fraction. This cytoskeletal rearrangement is not the cause of translational dormancy in sclerotia.

    Area of Science:

    • Cell Biology
    • Molecular Biology
    • Biochemistry

    Background:

    • The slime mold Physarum polycephalum transitions from an active plasmodial state to a dormant sclerotial state during starvation.
    • Protein synthesis is suppressed at the initiation level in sclerotia, despite the presence of functional mRNA and ribosomes.

    Purpose of the Study:

    • To investigate the role of cytoskeletal alterations in regulating protein synthesis during the transition from plasmodia to sclerotia.
    • To determine the distribution of polysomes and actin mRNA in cytoskeletal (CSK) and soluble (SOL) fractions of Physarum polycephalum.

    Main Methods:

    • Extraction of cytoskeletal (CSK) and soluble (SOL) fractions from Physarum polycephalum plasmodia and sclerotia using Triton X-100.
    • Analysis of polysome and actin mRNA distribution within these fractions.
    • Treatment with cycloheximide, an elongation inhibitor, to assess polysome dynamics.

    Main Results:

    • In plasmodia, most polysomes and actin mRNA reside in the CSK, while in sclerotia, they are primarily in the SOL.
    • Starvation induces a shift of translational components from CSK to SOL, correlating with suppressed protein synthesis.
    • Cycloheximide treatment causes polysome accumulation in the SOL of plasmodia, indicating limited CSK binding capacity.
    • Cycloheximide treatment causes polysome and mRNA accumulation in the CSK of sclerotia, demonstrating its capacity to bind translational components.

    Conclusions:

    • Alterations in the Physarum polycephalum cytoskeleton are not the primary mechanism for translational control during starvation-induced dormancy.
    • The shift of ribosomes and mRNA from the cytoskeleton to the soluble fraction is associated with, but not the cause of, suppressed protein synthesis.

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