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Abstract <p>Arsenic (As) is a toxic metalloid widespread in the environment, and many organisms have evolved mechanisms to mitigate its toxic effects. Bioinformatic analyses revealed that <i>acr3</i> genes are predominantly distributed in mushrooms, highlighting their evolutionary and functional importance in eukaryotic arsenic metabolism. In this study, two homologous genes, Hb<i>ACR3</i> and Hs<i>ACR3</i>, from the mushrooms <i>Hebeloma bulbiferum</i> and <i>Hebeloma sinapizans</i> were identified and functionally characterized. Both encode 399-amino-acid membrane proteins showing 99% sequence identity to each other and substantial similarity to previously characterized ACR3-type arsenite transporters from plants, yeasts, and bacteria. Heterologous expression of Hb<i>ACR3</i> and Hs<i>ACR3</i> in a <i>Saccharomyces cerevisiae arr3</i>Δ mutant restored resistance to arsenite and arsenate and significantly reduced intracellular arsenic accumulation. Fluorescence microscopy of GFP-tagged Hb<i>ACR3</i> and Hs<i>ACR3</i> confirmed their localization to the plasma membrane, consistent with an efflux transport function. Exposure of <i>H. bulbiferum</i> and <i>H. sinapizans</i> mycelia to arsenate led to a significant but differential transcriptional upregulation of both genes<i>.</i> This work provides new insight into the evolution, distribution, and physiological significance of ACR3 transporters in eukaryotic arsenic homeostasis.</p> Key points <p><UnorderedList Mark="Bullet"> <ItemContent> <p><i>Acr3 genes are widespread in fungi, indicating a key role in arsenic detoxification.</i></p> </ItemContent> <ItemContent> <p><i>HbACR3 and HsACR3 reduce cellular arsenic and confer As(III) tolerance.</i></p> </ItemContent> <ItemContent> <p><i>Arsenate exposure strongly induces HbACR3 and HsACR3 gene expression.</i></p> </ItemContent> </UnorderedList></p>

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Arsenic efflux mechanisms in ectomycorrhizal mushrooms Hebeloma bulbiferum and Hebeloma sinapizans

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月30日

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  • Jan Šnábl,
  • Gabriela Pelešková,
  • Antonín Kaňa,
  • Martina Šnáblová,
  • Tereza Leonhardt,
  • Jan Borovička,
  • Jan Sácký

摘要

Abstract

Arsenic (As) is a toxic metalloid widespread in the environment, and many organisms have evolved mechanisms to mitigate its toxic effects. Bioinformatic analyses revealed that acr3 genes are predominantly distributed in mushrooms, highlighting their evolutionary and functional importance in eukaryotic arsenic metabolism. In this study, two homologous genes, HbACR3 and HsACR3, from the mushrooms Hebeloma bulbiferum and Hebeloma sinapizans were identified and functionally characterized. Both encode 399-amino-acid membrane proteins showing 99% sequence identity to each other and substantial similarity to previously characterized ACR3-type arsenite transporters from plants, yeasts, and bacteria. Heterologous expression of HbACR3 and HsACR3 in a Saccharomyces cerevisiae arr3Δ mutant restored resistance to arsenite and arsenate and significantly reduced intracellular arsenic accumulation. Fluorescence microscopy of GFP-tagged HbACR3 and HsACR3 confirmed their localization to the plasma membrane, consistent with an efflux transport function. Exposure of H. bulbiferum and H. sinapizans mycelia to arsenate led to a significant but differential transcriptional upregulation of both genes. This work provides new insight into the evolution, distribution, and physiological significance of ACR3 transporters in eukaryotic arsenic homeostasis.

Key points

Acr3 genes are widespread in fungi, indicating a key role in arsenic detoxification.

HbACR3 and HsACR3 reduce cellular arsenic and confer As(III) tolerance.

Arsenate exposure strongly induces HbACR3 and HsACR3 gene expression.