# Myo5B plays a significant role in the hyphal growth and virulence of the human pathogenic fungus Mucor lusitanicus

## TL;DR

A protein called Myo5B is crucial for the growth and ability to cause disease in a deadly fungus, Mucor lusitanicus.

## Contribution

This study reveals the essential role of Myo5B in hyphal growth and virulence in Mucor lusitanicus, a human pathogenic fungus.

## Key findings

- Silencing Myo5B leads to reduced growth and sporulation in Mucor lusitanicus.
- The myo5BΔ mutant shows abnormal hyphal structures and avirulence in an invertebrate model.
- Myo5B is critical for dimorphism and pathogenicity in M. lusitanicus.

## Abstract

Mucormycosis is an emerging and deadly invasive fungal infection caused by fungi belonging to the Mucorales order. We investigated the myosin superfamily, which encompasses diverse actin-based motor proteins with various cellular functions. Specifically, the role of the Myo5B (ID 179665) protein from the myosin class V family in Mucor lusitanicus was explored by generating silencing phenotypes and null mutants corresponding to the myo5B gene. Silencing fungal transformants exhibited a markedly reduced growth rate and a nearly complete absence of sporulation compared to the wild-type strain. The myo5BΔ null mutant strain displayed atypical characteristics, including abnormally short septa and inflated hyphae. Notably, there were a majority of small yeast-like cells instead of filamentous hyphae in the mutant. These yeast-like cells cannot germinate normally, resulting in a loss of polarity. In vivo virulence assays conducted in the Galleria mellonella invertebrate model revealed that the myo5BΔ mutant strain was avirulent. These findings shed light on the crucial contributions of the Myo5B protein to the dimorphism and pathogenicity of M. lusitanicus. Therefore, the myosin V family is a potential target for future therapeutic interventions aimed at treating mucormycosis.