# Regulation of Autophagosome Membrane Dynamics by the Atg8 Family of Proteins

> **NIH NIH R01** · YALE UNIVERSITY · 2020 · $482,167

## Abstract

Macro-autophagy is the intracellular stress-response pathway by which the cell packages portions of
the cytosol for delivery into the lysosome. This “packaging” is carried out by the de novo formation of
a new organelle called the autophagosome that grows and encapsulates cytosolic material for
eventual lysosomal degradation. How autophagosomes form, including especially how the
membrane coordinates the capture of cytosolic toxins with its own expansion and closure is an area
of intense study. One factor implicated in both cargo-capture and autophagosome dynamics is the
ubiquitin-like protein, Atg8. During autophagy, Atg8 becomes covalently bound to
phosphatidylethanolamine (PE) on the preautophagosomal membrane and remains bound through
the maturation process of the autophagosome.
Our preliminary results suggest that Atg8-PE can directly deform the membrane perhaps contributing
to the unique cup-like morphology of the immature autophagosome. Further, we show that several
proteins driving Atg8 recruitment are designed to recognize unique features of the autophagosome
including curvature. By combining these low affinity interactions across multiple proteins in a complex,
these proteins would achieve dramatic targeting selectivity for only the transient intermediate in the
autophagosome growth. Once cargo-capture is complete and the autophagosome closes, curvature-
sensitive components are released. Atg8-PE must also eventually be recycled and we describe how
the proteases responsible for Atg8-PE release are also sensitive to the membrane structure and
composition. Our discoveries are made possible by two important technological advances. First we
have developed a variety of in vitro reconstitution approaches to study how Atg8-PE and other
autophagy proteins influence membrane deformation and structure. In particular, we have now
reconstituted Atg8-PE formation on Giant Unilamellar Vesicles that comprise both a highly tractable
membrane manipulation model and also are large enough to support fluorescent-microscopy based
interrogation of protein-membrane organization. Second, we can now image autophagosome
intermediate structures at super resolution in three dimensions so that we can now visualize both the
cup-like intermediate and its eventual resolution following fission.
With this proposal, we expect to demonstrate exactly how Atg8-PE proteins coordinate the dual
responsibilities of protein-protein interaction supporting cargo encapsulation with the protein-
membrane complexes that shape and close the autophagosome.

## Key facts

- **NIH application ID:** 9843155
- **Project number:** 5R01GM100930-08
- **Recipient organization:** YALE UNIVERSITY
- **Principal Investigator:** Thomas James Melia
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $482,167
- **Award type:** 5
- **Project period:** 2013-01-01 → 2020-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9843155

## Citation

> US National Institutes of Health, RePORTER application 9843155, Regulation of Autophagosome Membrane Dynamics by the Atg8 Family of Proteins (5R01GM100930-08). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9843155. Licensed CC0.

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