Genetic and cellular characterization of MscS-like putative channels in the filamentous fungus Aspergillus nidulans

ABSTRACT

Mechanosensitive ion channels are integral membrane proteins ubiquitously present in bacteria, archaea, and eukarya. They act as molecular sensors of mechanical stress to serve vital functions such as touch, hearing, osmotic pressure, proprioception and balance, while their malfunction is often associated with pathologies. Amongst them, the structurally distinct MscL and MscS channels from bacteria are the most extensively studied. MscS-like channels have been found in plants and Schizosaccharomyces pombe, where they regulate intracellular Ca²⁺ and cell volume under hypo-osmotic conditions. Here we characterize two MscS-like putative channels, named MscA and MscB, from the model filamentous fungus Aspergillus nidulans. Orthologues of MscA and MscB are present in most fungi, including relative plant and animal pathogens. MscA/MscB and other fungal MscS-like proteins share the three transmembrane helices and the extended C-terminal cytosolic domain that form the structural fingerprint of MscS-like channels with at least three additional transmembrane segments than Escherichia coli MscS. We show that MscA and MscB localize in Endoplasmic Reticulum and the Plasma Membrane, respectively, whereas their overexpression leads to increased CaCl₂ toxicity or/and reduction of asexual spore formation. Our findings contribute to understanding the role of MscS-like channels in filamentous fungi and relative pathogens.

KEYWORDS:

• Mechanosensitive
• ion channels
• MscS
• fungi
• AlphaFold

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

C.P. and G.D. conceived and designed the project. C.P., G.D., M.D., B.W., N.Y. performed research, processed and analysed the data. C.P. and G.D. wrote the manuscript, assisted by and M.D., B.W. and N.Y.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article [and/or] its supplementary materials.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19336950.2022.2098661

Additional information

Funding

This work was supported by the Biotechnology and Biological Sciences Research Council(BBSRC) [BB/S018069/1)] and [BB/W018411/1 – UK/EU(Greece) partnership) to C.P., who also acknowledges the Chinese Scholarship Council (CSC) in the form of studentships for B.W. and N.Y. MD is supported by the Stavros Niarchos Foundation [KE 14315].