Roles of Elm1 in antifungal susceptibility and virulence in Candida glabrata

Yuya Ito,Tatsuro Hirayama,Kazuko Yamamoto,Hironobu Nakayama,Hiroshi Mukae,Yoshifumi Imamura,Takashi Suematsu,Masato Tashiro,Akihiro Morita,Yutaka Tanaka,Shintaro Shimamura,Tomomi Saijo,Takahiro Takazono,Shigeru Kohno,Taiga Miyazaki,Katsunori Yanagihara,Koichi Izumikawa

doi:10.1038/s41598-020-66620-7

Abstract

Elm1 is a serine/threonine kinase involved in multiple cellular functions, including cytokinesis, morphogenesis, and drug resistance in Saccharomyces cerevisiae; however, its roles in pathogenic fungi have not been reported. In this study, we created ELM1-deletion, ELM1-reconstituted, ELM1-overexpression, and ELM1-kinase-dead strains in the clinically important fungal pathogen Candida glabrata and investigated the roles of Elm1 in cell morphology, stress response, and virulence. The elm1Δ strain showed elongated morphology and a thicker cell wall, with analyses of cell-wall components revealing that this strain exhibited significantly increased chitin content relative to that in the wild-type and ELM1-overexpression strains. Although the elm1Δ strain exhibited slower growth than the other two strains, as well as increased sensitivity to high temperature and cell-wall-damaging agents, it showed increased virulence in a Galleria mellonella-infection model. Moreover, loss of Elm1 resulted in increased adhesion to agar plates and epithelial cells, which represent important virulence factors in C. glabrata. Furthermore, RNA sequencing revealed that expression levels of 30 adhesion-like genes were elevated in the elm1Δ strain. Importantly, all these functions were mediated by the kinase activity of Elm1. To our knowledge, this is the first report describing the functional characterization of Elm1 in pathogenic fungi.

Highlights

Elm[1] is a serine/threonine kinase involved in multiple cellular functions, including cytokinesis, morphogenesis, and drug resistance in Saccharomyces cerevisiae; its roles in pathogenic fungi have not been reported
Similar to S. cerevisiae, the elm1Δ strain exhibited an elongated morphology in C. glabrata, which was restored to the yeast form by reintroduction of an intact ELM1 gene into the mutant (Fig. 1a)
Analysis of cell-wall components revealed that, there was no difference in the β-D-glucan content, the elm1Δ strain showed significantly increased chitin content as compared with the wild-type and ELM1-overexpression strains (Fig. 1d)

Summary

Introduction

Elm[1] is a serine/threonine kinase involved in multiple cellular functions, including cytokinesis, morphogenesis, and drug resistance in Saccharomyces cerevisiae; its roles in pathogenic fungi have not been reported. A previous report on drug resistance revealed that mutations in several genes, including CLA4, GIN4, and CDC28 functionally related to Elm[1] increase sensitivity to cycloheximide by inhibiting the transcription of PDR5 in S. cerevisiae[22]. These findings indicate that S. cerevisiae Elm[1] is regulated by calcineurin and exhibits various functions; its function and involvement in the virulence of the pathogenic fungus C. glabrata remain unknown. We elucidated the roles of Elm[1] in stress response and virulence in the clinically important fungal pathogen C. glabrata by generating elm1Δ, ELM1-overexpression, and ELM1-kinase dead (KD) strains

Methods

Results

Conclusion