Structural organization of p62 filaments and the cellular ultrastructure of calcium-rich p62-enwrapped lipid droplet cargo
The selective autophagy receptor p62/SQSTM1 is known to form higher-order filaments in vitro and to undergo liquid-liquid phase separation when mixed with poly-ubiquitin. Here, we determine the full-length cryo-EM structure of p62 and elucidate a structured double helical filament scaffold composed of the PB1-domain associated with the flexible C-terminal part and the solvent-accessible major groove. At different pH values and upon binding to soluble LC3, LC3-conjugated membranes and poly-ubiquitin, we observe p62 filament re-arrangements in the form of structural unwinding, disassembly, lateral association and bundling, respectively. In the cellular environment, under conditions of ATG5 knockdown leading to stalled autophagy, we imaged high-contrast layers consisting of p62 oligomers enwrapping lipid droplets by cryogenic electron tomography in situ, which we identified as calcium as well as phosphorus by compositional spectroscopy analysis. Together, we visualize the cellular ultrastructure of p62 oligomers with high calcium content as a potential early stage of autophagy.
Authors
- Peng‐Han Lu (ORCID: https://orcid.org/0000-0003-2696-6340)
- Sharma Likhesh (ORCID: https://orcid.org/0009-0005-5453-7414)
- Olivera Korculanin (ORCID: https://orcid.org/0000-0003-2109-6614)
- Carsten Sachse (ORCID: https://orcid.org/0000-0002-1168-5143)
- Lipi Thukral (ORCID: https://orcid.org/0000-0002-1961-039X)
- Jörg Fitter (ORCID: https://orcid.org/0000-0002-4503-2079)
- Lotte Ickert (ORCID: https://orcid.org/0000-0003-2729-0928)
- Natalia L. Kononenko (ORCID: https://orcid.org/0000-0002-3425-6659)
- Lisa Jungbluth (ORCID: https://orcid.org/0000-0002-5295-0521)
- Sabrina Berkamp (ORCID: https://orcid.org/0000-0002-9639-9698)
- Rafal E. Dunin–Borkowski (ORCID: https://orcid.org/0000-0001-8082-0647)
- Siavash Mostafavi (ORCID: https://orcid.org/0000-0002-4330-3285)
- Alexandros Katranidis (ORCID: https://orcid.org/0000-0002-1785-1659)
- Pitter F. Huesgen (ORCID: https://orcid.org/0000-0002-0335-2242)
- Maya M. Dierig (ORCID: https://orcid.org/0009-0003-3163-8242)
Institutions
- University of Freiburg (DE)
- Forschungszentrum Jülich (DE)
- Institute of Genomics and Integrative Biology (IN)
- University of Cologne (DE)
- Ernst Ruska Centre (DE)
- University Hospital Cologne (DE)
- Heinrich Heine University Düsseldorf (DE)
- RWTH Aachen University (DE)
- Academy of Scientific and Innovative Research (IN)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-11-28
- DOI
- https://doi.org/10.1038/s41467-025-66785-7
- Citations
- 1
- Primary Topic
- Autophagy in Disease and Therapy
- Type
- article
- Field-Weighted Citation Impact
- 1.35
Funders
- Alexander von Humboldt-Stiftung
- Boehringer Ingelheim Fonds
- Forschungszentrum Jülich