Biosynthesis of mitochondrial manganese superoxide dismutase in saccharomyces cerevisiae. Precursor form of mitochondrial superoxide dismutase made in the cytoplasm.
Biosynthesis of mitochondrial manganese superoxide dismutase in saccharomyces cerevisiae. Precursor form of mitochondrial superoxide dismutase made in the cytoplasm.
复制标题
酿酒酵母线粒体锰超氧化物歧化酶的生物合成。
DOI：
10.1016/s0021-9258(18)34982-2
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
A. P. Autor
中科院分区：
文献类型：
--
作者：
A. P. Autor
Manganese superoxide dismutase located in the mitochondrial matrix of yeast and all other eukaryotes is synthesized in the cytoplasm as a larger molecular weight precursor. This was shown by synthesis in a cell-free, reticulocyte lysate programmed with yeast RNA followed by immunoprecipitation of the radiolabeled translation products. The larger form of the Mn superoxide dismutase subunit was also detected in pulse-labeled spheroplasts after immunoprecipitation of the radiolabeled polypeptides. Disappearance of the radiolabeled precursor resulted when the spheroplasts were chased, thus leaving only the radiolabeled mature form detectable. Substantial homology was observed between the proteolytically cleaved peptides of the precursor and the mature forms of Mn superoxide dismutase polypeptides. De-energizing the mitochondrial membranes of intact yeast spheroplasts resulted in the accumulation of precursor Mn superoxide dismutase. This inhibition of the conversion of the precursor indicates that the Mn superoxide dismutase, like some other mitochondrial proteins, is dependent on energy for some aspect of the process. The synthesis of active Mn superoxide dismutase in yeast is dependent upon oxygen and may be controlled by some metabolic product of oxygen. Yeast grown under strict anaerobic conditions and containing less than 1.5% of the normal content of active cytochrome oxidase have no detectable superoxide dismutase activity assayed under the limitations of the method. Approximately 15% of the normal level of immunoreactive superoxide dismutase is present in anaerobic cells, however. Hemeless mutant (GL1) yeast, also known to be respiratory-deficient, contained a diminished amount of immunoprecipitable Mn superoxide dismutase as well as a diminished but measurable level of superoxide dismutase activity essentially quantitatively equivalent to the immunoreactive enzyme.In eukaryotic cells, manganese superoxide dismutase is found exclusively in the mitochondrial matrix where it catalytically removes superoxide anion radicals (1, 2). In addition, eukaryotic cells contain a Cu/Zn superoxide dismutase in the cytosol (1) and the mitochondrial intermembrane space (2-4). Recent reports present evidence that superoxide dismutase is also present in the nucleus (5). The two types of superoxide
