Temperature controls nuclear import of Tam3 transposase in Antirrhinum

Authors

  • Kaien Fujino,

    1. Laboratory of Crop Physiology, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
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    • Present address: Biotechnology Sector, Central Research Institute of Electronic Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194, Japan.

  • Shin-nosuke Hashida,

    1. Laboratory of Genetic Engineering, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
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    • Present address: Biotechnology Sector, Central Research Institute of Electronic Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194, Japan.

  • Takashi Ogawa,

    1. Laboratory of Plant Breeding, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
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  • Tomoko Natsume,

    1. Laboratory of Plant Breeding, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
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  • Takako Uchiyama,

    1. Laboratory of Plant Breeding, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
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  • Tetsuo Mikami,

    1. Laboratory of Genetic Engineering, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
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  • Yuji Kishima

    Corresponding author
    1. Laboratory of Plant Breeding, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
      (fax +81 11 706 4934; e-mail kishima@abs.agr.hokudai.ac.jp).
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  • These authors contributed equally to this work.

(fax +81 11 706 4934; e-mail kishima@abs.agr.hokudai.ac.jp).

Summary

It has been proposed that environmental stimuli can activate transposable elements (TEs), whereas few substantial mechanisms have been shown so far. The class-II element Tam3 from Antirrhinum majus exhibits a unique property of low-temperature-dependent transposition (LTDT). LTDT has proved invaluable in developing the gene isolation technologies that have underpinned much of modern plant developmental biology. Here, we reveal that LTDT involves differential subcellular localization of the Tam3 transposase (TPase) in cells grown at low (15°C) and high (25°C) temperatures. The mechanism is associated with the nuclear import of Tam3 TPase in Antirrhinum cells. At high temperature, the nuclear import of Tam3 TPase is severely restricted in Antirrhinum cells, whereas at low temperature, the nuclear localization of Tam3 TPase is observed in about 20% of the cells. However, in tobacco BY-2 and Allium cepa (onion) cells, Tam3 TPase is transported into most nuclei. In addition to three nuclear localization signals (NLSs), the Tam3 TPase is equipped with a nuclear localization inhibitory domain (NLID), which functions to abolish nuclear import of the TPase at high temperature in Antirrhinum. NLID in Tam3 TPase is considered to interact with Antirrhinum-specific factor(s). The host-specific regulation of the nuclear localization of transposase represents a new repertoire controlling class-II TEs.

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