TY - JOUR
T1 - Factors controlling the uptake of yeast copper/zinc superoxide dismutase into mitochondria
AU - Field, Lori Sturtz
AU - Furukawa, Yoshiaki
AU - O'Halloran, Thomas V.
AU - Culotta, Valeria Cizewski
PY - 2003/7/25
Y1 - 2003/7/25
N2 - We have previously shown that a fraction of yeast copper/zinc-superoxide dismutase (SOD1) and its copper chaperone CCS localize to the intermembrane space of mitochondria. In the present study, we have focused on the mechanism by which SOD1 is partitioned between cytosolic and mitochondrial pools. Using in vitro mitochondrial import assays, we show that only a very immature form of the SOD1 polypeptide that is apo for both copper and zinc can efficiently enter the mitochondria. Moreover, a conserved disulfide in SOD1 that is essential for activity must be reduced to facilitate mitochondrial uptake of SOD1. Once inside the mitochondria, SOD1 is converted to an active holo enzyme through the same post-translational modifications seen with cytosolic SOD1. The presence of high levels of CCS in the mitochondrial intermembrane space results in enhanced mitochondrial accumulation of SOD1, and this apparently involves CCS-mediated retention of SOD1 within mitochondria. This retention of SOD1 is not dependent on copper loading of the enzyme but does require protein-protein interactions at the heterodimerization interface of SOD1 and CCS as well as conserved cysteine residues in both molecules. A model for how CCS-mediated post-translational modification of SOD1 controls its partitioning between the mitochondria and cytosol will be presented.
AB - We have previously shown that a fraction of yeast copper/zinc-superoxide dismutase (SOD1) and its copper chaperone CCS localize to the intermembrane space of mitochondria. In the present study, we have focused on the mechanism by which SOD1 is partitioned between cytosolic and mitochondrial pools. Using in vitro mitochondrial import assays, we show that only a very immature form of the SOD1 polypeptide that is apo for both copper and zinc can efficiently enter the mitochondria. Moreover, a conserved disulfide in SOD1 that is essential for activity must be reduced to facilitate mitochondrial uptake of SOD1. Once inside the mitochondria, SOD1 is converted to an active holo enzyme through the same post-translational modifications seen with cytosolic SOD1. The presence of high levels of CCS in the mitochondrial intermembrane space results in enhanced mitochondrial accumulation of SOD1, and this apparently involves CCS-mediated retention of SOD1 within mitochondria. This retention of SOD1 is not dependent on copper loading of the enzyme but does require protein-protein interactions at the heterodimerization interface of SOD1 and CCS as well as conserved cysteine residues in both molecules. A model for how CCS-mediated post-translational modification of SOD1 controls its partitioning between the mitochondria and cytosol will be presented.
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U2 - 10.1074/jbc.M304296200
DO - 10.1074/jbc.M304296200
M3 - Article
C2 - 12748182
AN - SCOPUS:0041344579
SN - 0021-9258
VL - 278
SP - 28052
EP - 28059
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 30
ER -