Role of the Fusarium oxysporum metallothionein Mt1 in resistance to metal toxicity and virulence

作者：Damaris Lorenzo-Gutiérrez, Lucía Gómez-Gil, Josep Guarro, M. Isabel G. Roncero, Ana Fernández-Bravo, Javier Capilla, Loida López‐Fernández · 发表于：Metallomics · 年份：2019 · DOI：10.1039/c9mt00081j · 被引用次数：33 · 研究领域：Geochemistry and Elemental Analysis、Aluminum toxicity and tolerance in plants and animals、Radioactive element chemistry and processing

Soil organisms exhibit high tolerance to heavy metals, probably acquired through evolutionary adaptation to contaminated environments. Essentially, metal tolerance in fungi involves several specific and non-specific mechanisms that include metal efflux, metal binding to cell walls, extracellular and intracellular sequestration and complexation with proteins. However, fungi have adopted different strategies to detoxify heavy metals, although species differ in the mechanisms used. In this complex molecular framework, metallothioneins (MTs) are becoming increasingly relevant in metal homeostasis, even though little is known about their role in metal adaptation and virulence in fungal pathogens. With the aim to decipher the function of metallothioneins in the opportunistic fungus Fusarium oxysporum, we have carried out an in silico analysis that revealed the presence of a hypothetical metallothionein (mt1) that has multiple metal responsive elements in its promoter region and conserved cysteine motifs in its coding sequence. Characterization of strain Δmt1 deficient in the mt1 gene revealed higher sensitivity of this mutant to copper, cadmium and zinc compared to the wild type strain (wt). Expression analyses revealed that Zn specifically activates mt1, but the lack of this gene did not lead to a transcriptional up-regulation of genes gapdh and prx, associated with the oxidative stress response. The lack of mt1 did not alter the pathogenic capacity of the fungus, either in tomato...