Mutants of Saccharomyces cerevisiae defective in vacuolar function confirm a role for the vacuole in toxic metal ion detoxification

Abstract

To directly define vacuolar role(s) in metal detoxification, we have examined the responses of vacuole-deficient mutants of Saccharomyces cerevisiae to several potentially toxic metals known to be mainly detoxified in the cytosol (Cu, Cd) or the vacuole (Co, Mn, Ni, Zn). Three mutants, deficient in targeting of vacuolar proteins, were used with JSR18 delta 1 being devoid of any vacuole-like structure while ScVatB and ScVatC were deficient in specific protein subunits of the V-ATPase. The results obtained show that the absence of a vacuole or a functional vacuolar H(+)-ATPase was associated with increased sensitivity and a largely decreased capacity of the vacuole-deficient strains to accumulate Zn, Mn, Co and Ni, confirming an essential role for the vacuole in detoxification of these metals. In addition, the lack of vacuolar involvement in detoxification of Cu and Cd was confirmed since these metals did not exhibit increased toxicity towards the vacuolar mutants nor were there significant differences in Cu or Cd accumulation between parental and mutant strains.

A HOPS Protein, MoVps41, Is Crucially Important for Vacuolar Morphogenesis, Vegetative Growth, Reproduction and Virulence in Magnaporthe oryzae

“…However, research demonstrations have shown that, the intracellular accumulation of these cations beyond certain physiological limit turn to impact negatively (metal ion toxicity) on fungal growth and development. Sequestering activities of the vacuole play an important role in shielding cells from the harmful effects of toxic metal ions and also crucially mediate the detoxification of these metal ions (Ramsay and Gadd, 1997). To examine the contribution of MoVps41 in vacuolar sequestering and subsequent detoxification of metal ions, we monitored the vegetative growth ΔMovps41 mutant, Guy11 wild-type and the C-21 complemented strain on 1/4 YG growth medium supplemented with defined concentration of divalent metal ions.…”

MrpacC regulates sporulation, insect cuticle penetration and immune evasion in Metarhizium robertsii

“…S3). It has been well established in yeasts and plants that the vacuole is the primary organelle for accumulation and detoxification of metal ions (Ramsay and Gadd, 1997;Tong et al, 2004). In this respect, smaller vacuoles in ΔMrpacC could account for its reduced ability for ion tolerance.…”

Manganese Homeostasis in Saccharomyces cerevisiae

“…The first clues implicating the role of vacuoles in metal-ion homeostasis came with genetic studies utilizing yeast strains defective in vacuolar biogenesis and function; these strains exhibited growth defects when exposed to a host of transition metal salts, including cobalt, manganese, iron, nickel, copper, zinc, and cadmium 85,86. Indeed, manganese is more concentrated in the vacuole than in the cytosol, thereby providing a site with which to sequester toxic excess levels of cellular manganese that can potentially wreak havoc in a variety of cellular compartments 6,86,87. Thus far, one vacuolar manganese transport pathway has been definitively identified, Ccc1p 6,88,89.…”