Oligomerization of p62 allows for selection of ubiquitinated cargo and isolation membrane during selective autophagy

Abstract

Autophagy is a major pathway for the clearance of harmful material from the cytoplasm. During autophagy cytoplasmic material is delivered into the lysosomal system by organelles called autophagosomes. Autophagosomes form in a de novo manner and, in the course of their formation, isolate cargo material from the rest of the cytoplasm. Cargo specificity is conferred by autophagic cargo receptors that selectively link the cargo to the autophagosomal membrane decorated with ATG8 family proteins such as LC3B. Here we show that the human cargo receptor p62/SQSTM-1 employs oligomerization to stabilize its interaction with LC3B and linear ubiquitin when they are clustered on surfaces. Thus, oligomerization enables p62 to simultaneously select for the isolation membrane and the ubiquitinated cargo. We further show in a fully reconstituted system that the interaction of p62 with ubiquitin and LC3B is sufficient to bend the membrane around the cargo.

Article and author information

Author details

  1. Bettina Wurzer

    Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
  2. Gabriele Zaffagnini

    Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
  3. Dorotea Fracchiolla

    Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
  4. Eleonora Turco

    Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
  5. Christine Abert

    Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
  6. Julia Romanov

    Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
    Competing interests
    The authors declare that no competing interests exist.
  7. Sascha Martens

    Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
    For correspondence
    sascha.martens@univie.ac.at
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Randy Schekman, Howard Hughes Medical Institute, University of California, Berkeley, United States

Publication history

  1. Received: May 24, 2015
  2. Accepted: September 26, 2015
  3. Accepted Manuscript published: September 28, 2015 (version 1)
  4. Version of Record published: November 30, 2015 (version 2)

Copyright

© 2015, Wurzer et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Metrics

  • 6,155
    Page views
  • 1,742
    Downloads
  • 153
    Citations

Article citation count generated by polling the highest count across the following sources: Scopus, Crossref, PubMed Central.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Bettina Wurzer
  2. Gabriele Zaffagnini
  3. Dorotea Fracchiolla
  4. Eleonora Turco
  5. Christine Abert
  6. Julia Romanov
  7. Sascha Martens
(2015)
Oligomerization of p62 allows for selection of ubiquitinated cargo and isolation membrane during selective autophagy
eLife 4:e08941.
https://doi.org/10.7554/eLife.08941

Further reading

    1. Biochemistry and Chemical Biology
    2. Microbiology and Infectious Disease
    Abhinay Ramaprasad, Paul-Christian Burda ... Michael J Blackman
    Research Article Updated

    The malaria parasite Plasmodium falciparum synthesizes significant amounts of phospholipids to meet the demands of replication within red blood cells. De novo phosphatidylcholine (PC) biosynthesis via the Kennedy pathway is essential, requiring choline that is primarily sourced from host serum lysophosphatidylcholine (lysoPC). LysoPC also acts as an environmental sensor to regulate parasite sexual differentiation. Despite these critical roles for host lysoPC, the enzyme(s) involved in its breakdown to free choline for PC synthesis are unknown. Here, we show that a parasite glycerophosphodiesterase (PfGDPD) is indispensable for blood stage parasite proliferation. Exogenous choline rescues growth of PfGDPD-null parasites, directly linking PfGDPD function to choline incorporation. Genetic ablation of PfGDPD reduces choline uptake from lysoPC, resulting in depletion of several PC species in the parasite, whilst purified PfGDPD releases choline from glycerophosphocholine in vitro. Our results identify PfGDPD as a choline-releasing glycerophosphodiesterase that mediates a critical step in PC biosynthesis and parasite survival.

    1. Biochemistry and Chemical Biology
    2. Structural Biology and Molecular Biophysics
    Jiemin Shen, Azaan Saalim Wilbon ... Yaping Pan
    Research Article Updated

    Ferroportin (Fpn) is a transporter that releases ferrous ion (Fe2+) from cells and is important for homeostasis of iron in circulation. Export of one Fe2+ by Fpn is coupled to import of two H+ to maintain charge balance. Here, we show that human Fpn (HsFpn) binds to and mediates Ca2+ transport. We determine the structure of Ca2+-bound HsFpn and identify a single Ca2+ binding site distinct from the Fe2+ binding sites. Further studies validate the Ca2+ binding site and show that Ca2+ transport is not coupled to transport of another ion. In addition, Ca2+ transport is significantly inhibited in the presence of Fe2+ but not vice versa. Function of Fpn as a Ca2+ uniporter may allow regulation of iron homeostasis by Ca2+.