Previous Article | Next Article ![]()
Mol. Cell. Biol., 11 1996, 6303-6312, Vol 16, No. 11
SJ Lin and VC Culotta
Oxygen toxicity in Saccharomyces cerevisiae lacking the copper/zinc
superoxide dismutase (SOD1) can be suppressed by overexpression of the S.
cerevisiae ATX2 gene. Multiple copies of ATX2 were found to reverse the
aerobic auxotrophies of sod1(delta) mutants for lysine and methionine and
also to enhance the resistance of these yeast strains to paraquat and
atmospheric levels of oxygen. ATX2 encodes a novel 34.4- kDa polypeptide
with a number of potential membrane-spanning domains. Our studies indicate
that Atx2p localizes to the membrane of a vesicular compartment in yeast
cells reminiscent of the Golgi apparatus. With indirect immunofluorescence
microscopy, Atx2p exhibited a punctate pattern of staining typical of the
Golgi apparatus, and upon subcellular fractionation, Atx2p colocalized with
a biochemical marker for the yeast Golgi apparatus. We demonstrate here
that this vesicle protein normally functions in the homeostasis of
manganese ions and that this role in metal metabolism is necessary for the
ATX1 suppression of SOD1 deficiency. First, overexpression of ATX2 caused
cells to accumulate increased levels of manganese. Second, a deletion in
ATX2 caused a decrease in the apparent available level of intracellular
manganese and caused sod1(delta) mutants to become dependent upon exogenous
manganese for aerobic growth. Third, ATX2 was incapable of suppressing
oxidative damage in cells depleted of manganese ions or lacking the plasma
membrane transporter for manganese. The effect of ATX2 overexpression on
manganese accumulation and oxygen resistance is similar to what we have
previously reported for mutations in PMR1, which encodes a
manganese-trafficking protein that also resides in a vesicular compartment.
Our studies are consistent with a model in which Atx2p and Pmr1p work in
opposite directions to control manganese homeostasis.
Copyright © 1996, American Society for Microbiology
Suppression of oxidative damage by Saccharomyces cerevisiae ATX2, which encodes a manganese-trafficking protein that localizes to Golgi-like vesicles
Department of Environmental Health Sciences, The Johns Hopkins University School of Hygiene and Public Health, Baltimore, Maryland 21205, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»