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Crystallizing Membrane Proteins for Structure Determination using Lipidic Mesophases
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Crystallizing Membrane Proteins for Structure Determination using Lipidic Mesophases

Published on: November 21, 2010

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Polylysine is a Proteostasis Network-Engaging Structural Determinant

Wei-Han Lang, Giulia Calloni, R Martin Vabulas

    Journal of Proteome Research
    |April 11, 2018
    PubMed

    Insights

    C-terminal polylysine (PL) triggers a cellular stress response. This study identifies key protein machinery in the cytosol that processes PL and reveals its novel association with nuclear transport, suggesting a new protein quality control pathway.

    Area of Science:

    • Cellular Biology
    • Protein Homeostasis
    • Molecular Mechanisms

    Background:

    • C-terminal polylysine (PL) synthesis occurs due to mRNA processing errors.
    • PL's positive charge causes ribosomal stalling, activating the Ribosome-associated quality control (RQC) complex.
    • RQC dysfunction leads to toxic PL-tagged protein accumulation and cellular stress.

    Purpose of the Study:

    • To investigate the specific protein quality control mechanisms for PL-tagged proteins.
    • To identify the cytosolic machinery involved in post-ribosomal PL processing.
    • To explore the interaction of PL with cellular transport systems.

    Main Methods:

    • Quantitative mass spectrometry to identify protein interactions.
    • Analysis of cytosolic protein complexes involved in proteostasis.
    • Investigating the role of nuclear transport machinery in PL handling.

    Main Results:

    • The study identified key cytosolic proteostasis network components, including TRiC chaperonins and proteasomes, involved in PL processing.
    • A novel association between PL-tagged polypeptides and the nuclear transport machinery was discovered.
    • Experimental evidence confirmed enhanced nuclear import of PL-tagged proteins, suggesting compartmentalization.

    Conclusions:

    • A previously unknown post-ribosomal PL-processing pathway exists in the human cytosol.
    • The nuclear transport machinery plays a role in handling PL-tagged proteins.
    • This suggests a novel cellular strategy for managing aberrant protein products.

    Keywords:
    chaperonepolylysineproteasomeprotein degradationprotein quality controltranslational read-through

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