Talemi2014 - Arsenic toxicity and detoxification mechanisms in yeast

Talemi2014 - Arsenic toxicity and
detoxification mechanisms in yeast
The model implements arsenite (AsIII)
transport regulation, its distribution within main cellular AsIII
pools and detoxification. The intracellular As pools considered are
free AsIII (AsIIIin), protein-bound AsIII (AsIIIprot), glutathione
conjugated AsIII (AsGS3) and vacuolar sequestered AsIII (vAsGS3).

This model is described in the article:

Mathematical modelling of
arsenic transport, distribution and detoxification processes in
yeast.

Talemi SR, Jacobson T, Garla V,
Navarrete C, Wagner A, Tamás MJ, Schaber J.
Mol. Microbiol. 2014 Jun; 92(6):
1343-1356
Abstract:

Arsenic has a dual role as causative and curative agent of
human disease. Therefore, there is considerable interest in
elucidating arsenic toxicity and detoxification mechanisms. By
an ensemble modelling approach, we identified a best
parsimonious mathematical model which recapitulates and
predicts intracellular arsenic dynamics for different
conditions and mutants, thereby providing novel insights into
arsenic toxicity and detoxification mechanisms in yeast, which
could partly be confirmed experimentally by dedicated
experiments. Specifically, our analyses suggest that: (i)
arsenic is mainly protein-bound during short-term (acute)
exposure, whereas glutathione-conjugated arsenic dominates
during long-term (chronic) exposure, (ii) arsenic is not stably
retained, but can leave the vacuole via an export mechanism,
and (iii) Fps1 is controlled by Hog1-dependent and
Hog1-independent mechanisms during arsenite stress. Our results
challenge glutathione depletion as a key mechanism for arsenic
toxicity and instead suggest that (iv) increased glutathione
biosynthesis protects the proteome against the damaging effects
of arsenic and that (v) widespread protein inactivation
contributes to the toxicity of this metalloid. Our work in
yeast may prove useful to elucidate similar mechanisms in
higher eukaryotes and have implications for the use of arsenic
in medical therapy.

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