Localization of a DNA topoisomerase II to mitochondria inDictyostelium discoideum: Deletion mutant analysis and mitochondrial targeting signal presequence |
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Authors: | Kayoko Komori Fumiaki Maruo Takahiro Morio Hideko Urushihara Yoshimasa Tanaka |
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Affiliation: | (1) Institute of Biological Sciences, University of Tsukuba, Tsukuba, 305 Ibaraki, Japan;(2) Center for TARA, University of Tsukuba, Tsukuba, 305 Ibaraki, Japan;(3) Present address: Department of Molecular Biology, Biomolecular Engineering Research Institute (BERI), Furuedai 6-2-3, Suita, 565 Osaka, Japan |
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Abstract: | DNA topoisomerase II ofDictyostelium discoideum (TopA), the gene (topA) encoding which we cloned, was shown to have an additional N-terminal region which contains a putative mitochondrial targeting
signal presequence. We constructed overexpression mutants which expressed the wild-type or the N-terminally deleted enzyme,
and examined its localization by immunofluorescence microscopy and proteinase K digestion experiment. These experiments revealed
that the enzyme is located in the mitochondria by virtue of the additional N-terminal region. Furthermore, in the cell extract
depleted the enzyme by immunoprecipitation, nuclear DNA topoisomerase II activity was not decreased. These results confirmed
that TopA is located in the mitochondria, even through its amino acid sequence is highly similar to those of nuclear type
topoisomerase II of other organisms. Thus, this report is the first to establish the location of the mitochondrial targeting
signal presequence in DNA topoisomerase II and in proteins ofD. discoideum directly by analyzing deletion mutants.
Tsukuba Advanced Research Alliance (TARA researcher for the Sakabe project) |
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Keywords: | Dictyostelium discoideum DNA topoisomerase II Localization Mitochondria Signal sequence |
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