# MYO5A-mediated stabilization promotes the acquisition of fusion competence in sealed autophagosomes

## TL;DR

This study shows that MYO5A helps autophagosomes mature and fuse with lysosomes, which is crucial for autophagy to function properly.

## Contribution

The study identifies MYO5A as a conserved regulator of autophagosome-lysosome fusion through its LIR motifs.

## Key findings

- MYO5A is essential for autophagosome-lysosome fusion in yeast, mammalian cells, and C. elegans.
- Loss of MYO5A disrupts the localization of fusion machinery and reduces stationary autophagosomes.
- MYO5A binds to autophagosomes via two LIR motifs in its coiled-coil and globular tail domains.

## Abstract

Autophagy requires precise regulation of autophagosome-lysosome fusion, yet the molecular details of this process remain incompletely understood. Here, we identify the class V myosin MYO5A as a critical regulator of autophagic flux. The genetic or pharmacological inhibition of MYO5A in Saccharomyces cerevisiae, mammalian cells, or Caenorhabditis elegans blocked autophagic flux by preventing autophagosome-lysosome fusion. MYO5A facilitates the maturation of autophagosomes into fusion-competent intermediates as its loss altered the localization of fusion machinery on autophagosomes and reduced the pool of stationary autophagosomes, a step that proved critical for subsequent fusion with lysosomes. Domain mapping and targeted mutagenesis revealed that two LIR motifs (PAYRVL and QAYIGL) within the coiled-coil and globular tail domains of MYO5A mediate its direct interaction with LC3 on autophagosomes. Live imaging in mammalian cells and C. elegans added support for this role, revealing how MYO5A regulates autophagic flux to ensure fusion. Together, these findings establish MYO5A as a regulator of autophagy and highlight its potential as a target for fine-tuning autophagic flux.

During autophagy, autophagosomes are completely sealed before fusing to lysosomes and releasing their cargo. In this study, MYO5A is shown to reduce directional switching in late stage autophagosomes, enabling maturation into fusion-competent intermediates.

MYO5A is essential for autophagosome–lysosome fusion, with its loss blocking autophagic flux in yeast, mammalian cells, and C. elegans.MYO5A functions during late stages of autophagy, promoting the transition of autophagosomes into fusion-competent intermediates.Loss of MYO5A function mis-localizes core fusion machinery and significantly reduces the stationary autophagosome population required for efficient fusion.MYO5A binds autophagosomes via its two LIR motifs in its coiled-coil and globular tail regions.MYO5A is a conserved regulator ensuring proper autophagic flux.

MYO5A is essential for autophagosome–lysosome fusion, with its loss blocking autophagic flux in yeast, mammalian cells, and C. elegans.

MYO5A functions during late stages of autophagy, promoting the transition of autophagosomes into fusion-competent intermediates.

Loss of MYO5A function mis-localizes core fusion machinery and significantly reduces the stationary autophagosome population required for efficient fusion.

MYO5A binds autophagosomes via its two LIR motifs in its coiled-coil and globular tail regions.

MYO5A is a conserved regulator ensuring proper autophagic flux.

MYO5A interacts with autophagosomes via its LIR motifs and promotes their fusion competence by reducing their directional movement.