# Acetylation dynamics of MrATG4 governing autophagy-mediated conidiation in an entomopathogenic fungus

## TL;DR

This study explores how acetylation of the protein MrATG4 affects autophagy and spore production in a fungus used for pest control.

## Contribution

The first evidence that acetylation of ATG4 regulates autophagy and conidiation in fungi.

## Key findings

- Deletion of MrSIR2–3 increases autophagy and impairs conidiation.
- Deletion of MrKAT1 suppresses autophagy and also impairs conidiation.
- MrATG4 acetylation is regulated by MrKAT1 and MrSIR2–3, affecting autophagy homeostasis.

## Abstract

Conidial production is a critical factor determining the efficacy of entomopathogenic fungi as biocontrol agents. Autophagy, a fundamental cellular degradation process, plays an essential role in regulating fungal conidiation. However, the modulation of autophagy through acetylation, particularly concerning the autophagy-related protein ATG4, remains poorly understood in fungi. Here, we investigate the roles of the deacetylase MrSIR2–3 and the acetyltransferase MrKAT1 in Metarhizium robertsii, focusing on their impacts on autophagy and conidiation. Our findings demonstrate that deletion of MrSIR2–3 (ΔMrsir2–3) leads to elevated autophagy levels, whereas loss of MrKAT1 (ΔMrkat1) suppresses autophagy initiation; both alterations consequently impair conidiation. Interaction assays further reveal that the key autophagy factor MrATG4 is regulated by opposing acetylation and deacetylation mediated by MrKAT1 and MrSIR2–3, potentially via modification of lysine residues K69 and/or K77. This dynamic acetylation balance is essential for maintaining autophagy homeostasis and ensuring efficient conidiation. Collectively, our results provide novel insights into how the acetylation of ATG4 modulates autophagy, advancing our understanding of conidiation regulation in entomopathogenic fungi and highlighting potential targets for enhancing fungal biocontrol efficacy.

Autophagy is a vital cellular process that supports growth and reproduction in fungi by forming autophagosomes to digest and recycle cellular components. In this study, we explore the role of the autophagy-related protein MrATG4 in the autophagy and conidiation of the entomopathogenic fungus Metarhizium robertsii, a widely used biopesticide for natural pest control. We focus on the regulatory roles of MrSIR2–3, a deacetylase, and MrKAT1, an acetyltransferase, in modulating the acetylation status of MrATG4. Our findings reveal that deletion of MrSIR2–3 enhances autophagy, whereas deletion of MrKAT1 suppresses it, both significantly impacting conidia production. This study provides the first evidence that acetylation of ATG4 is crucial for autophagy and conidia formation in fungi. These insights deepen our understanding of fungal growth and reproductive regulation and offer potential strategies for optimizing biological pest control.