Molecular mechanism to target the endosomal Mon1-Ccz1 GEF complex to the pre-autophagosomal structure

  1. Jieqiong Gao
  2. Lars Langemeyer
  3. Daniel Kuemmel
  4. Fulvio Reggiori
  5. Christian Ungermann  Is a corresponding author
  1. University of Osnabrück, Germany
  2. University of Groningen, University Medical Center Groningen, Netherlands

Abstract

During autophagy, a newly formed double membrane surrounds its cargo to generate the so-called autophagosome, which then fuses with a lysosome after closure. Previous work implicated that endosomal Rab7/Ypt7 associates to autophagosomes prior to their fusion with lysosomes. Here, we unravel how the Mon1-Ccz1 guanosine exchange factor (GEF) acting upstream of Ypt7 is specifically recruited to the pre-autophagosomal structure under starvation conditions. We find that Mon1-Ccz1 directly binds to Atg8, the yeast homolog of the members of the mammalian LC3 protein family. This requires at least one LIR motif in the Ccz1 C-terminus, which is essential for autophagy but not for endosomal transport. In agreement, only wild-type, but not LIR-mutated Mon1-Ccz1 promotes Atg8-dependent activation of Ypt7. Our data reveal how GEF targeting can specify the fate of a newly formed organelle and provide new insights into the regulation of autophagosome-lysosome fusion.

Article and author information

Author details

  1. Jieqiong Gao

    Department of Biology and Chemistry, Biochemistry section, University of Osnabrück, Osnabrück, Germany
    Competing interests
    The authors declare that no competing interests exist.
  2. Lars Langemeyer

    Department of Biology and Chemistry, Biochemistry section, University of Osnabrück, Osnabrück, Germany
    Competing interests
    The authors declare that no competing interests exist.
  3. Daniel Kuemmel

    Department of Biology and Chemistry, Structural Biology section, University of Osnabrück, Osnabrück, Germany
    Competing interests
    The authors declare that no competing interests exist.
  4. Fulvio Reggiori

    Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
    Competing interests
    The authors declare that no competing interests exist.
  5. Christian Ungermann

    Department of Biology and Chemistry, Biochemistry section, University of Osnabrück, Osnabrück, Germany
    For correspondence
    cu@uos.de
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4331-8695

Funding

Deutsche Forschungsgemeinschaft (UN111/7-3)

  • Christian Ungermann

Deutsche Forschungsgemeinschaft (SFB 944)

  • Daniel Kuemmel

ZonMw (VICI 016.130.606)

  • Fulvio Reggiori

European Commission (Marie Skłodowska-Curie ITN)

  • Fulvio Reggiori

Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (SNF Sinergia (CRSII3_154421)

  • Fulvio Reggiori

Deutsche Forschungsgemeinschaft (SFB 944)

  • Christian Ungermann

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Noboru Mizushima, The University of Tokyo, Japan

Version history

  1. Received: August 9, 2017
  2. Accepted: February 12, 2018
  3. Accepted Manuscript published: February 15, 2018 (version 1)
  4. Version of Record published: March 7, 2018 (version 2)

Copyright

© 2018, Gao 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

  • 3,831
    Page views
  • 661
    Downloads
  • 56
    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. Jieqiong Gao
  2. Lars Langemeyer
  3. Daniel Kuemmel
  4. Fulvio Reggiori
  5. Christian Ungermann
(2018)
Molecular mechanism to target the endosomal Mon1-Ccz1 GEF complex to the pre-autophagosomal structure
eLife 7:e31145.
https://doi.org/10.7554/eLife.31145

Share this article

https://doi.org/10.7554/eLife.31145

Further reading

    1. Biochemistry and Chemical Biology
    Jake W Anderson, David Vaisar ... Natalie G Ahn
    Research Article

    Activation of the extracellular signal-regulated kinase-2 (ERK2) by phosphorylation has been shown to involve changes in protein dynamics, as determined by hydrogen-deuterium exchange mass spectrometry (HDX-MS) and NMR relaxation dispersion measurements. These can be described by a global exchange between two conformational states of the active kinase, named ‘L’ and ‘R,’ where R is associated with a catalytically productive ATP-binding mode. An ATP-competitive ERK1/2 inhibitor, Vertex-11e, has properties of conformation selection for the R-state, revealing movements of the activation loop that are allosterically coupled to the kinase active site. However, the features of inhibitors important for R-state selection are unknown. Here, we survey a panel of ATP-competitive ERK inhibitors using HDX-MS and NMR and identify 14 new molecules with properties of R-state selection. They reveal effects propagated to distal regions in the P+1 and helix αF segments surrounding the activation loop, as well as helix αL16. Crystal structures of inhibitor complexes with ERK2 reveal systematic shifts in the Gly loop and helix αC, mediated by a Tyr-Tyr ring stacking interaction and the conserved Lys-Glu salt bridge. The findings suggest a model for the R-state involving small movements in the N-lobe that promote compactness within the kinase active site and alter mobility surrounding the activation loop. Such properties of conformation selection might be exploited to modulate the protein docking interface used by ERK substrates and effectors.

    1. Biochemistry and Chemical Biology
    Anne E Hultgren, Nicole MF Patras, Jenna Hicks
    Feature Article

    Organizations that fund research are keen to ensure that their grant selection processes are fair and equitable for all applicants. In 2020, the Arnold and Mabel Beckman Foundation introduced blinding to the first stage of the process used to review applications for Beckman Young Investigator (BYI) awards: applicants were instructed to blind the technical proposal in their initial Letter of Intent by omitting their name, gender, gender-identifying pronouns, and institutional information. Here we examine the impact of this change by comparing the data on gender and institutional prestige of the applicants in the first four years of the new policy (BYI award years 2021–2024) with data on the last four years of the old policy (2017–2020). We find that under the new policy, the distribution of applicants invited to submit a full application shifted from those affiliated with institutions regarded as more prestigious to those outside of this group, and that this trend continued through to the final program awards. We did not find evidence of a shift in the distribution of applicants with respect to gender.