R. Balzan et al., ESCHERICHIA-COLI IRON SUPEROXIDE-DISMUTASE TARGETED TO THE MITOCHONDRIA OF YEAST-CELLS PROTECTS THE CELLS AGAINST OXIDATIVE STRESS, Proceedings of the National Academy of Sciences of the United Statesof America, 92(10), 1995, pp. 4219-4223
A gene encoding a fusion protein consisting of Escherichia coli iron s
uperoxide dismutase (FeSOD) with the mitochondrial targeting presequen
ce of yeast manganese superoxide dismutase (MnSOD) was cloned and expr
essed in E. coli and in Saccharomyces cerevisiae DL1Mn(-) yeast cells
deficient in MnSOD. In the yeast cells the fusion protein was imported
into the mitochondrial matrix. However, the presequence was not cleav
ed. In a control set of experiments, the E. coli FeSOD gene without th
e yeast MnSOD leader sequence was also cloned and expressed in S. cere
visiae DL1Mn(-) cells. In this case the FeSOD was located in the cytos
ol and was not imported into the mitochondrial matrix. E. coli FeSOD,
with and without the yeast MnSOD presequence, proved to be active in y
east, but, whereas the FeSOD targeted to the mitochondria of yeast cel
ls deficient in MnSOD protected the cells from the toxic effects of ox
idative stress, FeSOD without the yeast MnSOD presequence did not prot
ect the yeast cells deficient in MnSOD against oxidative stress.