The plant-specific family of DNA-binding proteins containing three HMG-box domains interacts with mitotic and meiotic chromosomes

Authors

  • Dorthe S. Pedersen,

    1. Cell Biology and Plant Biochemistry, Regensburg University, Universitätsstr. 31, D-93053 Regensburg, Germany
    2. Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark
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    • These authors contributed equally to this work.

  • Frederik Coppens,

    1. Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium
    2. Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
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    • These authors contributed equally to this work.

  • Lu Ma,

    1. Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, D-06466 Gatersleben, Germany
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  • Martin Antosch,

    1. Cell Biology and Plant Biochemistry, Regensburg University, Universitätsstr. 31, D-93053 Regensburg, Germany
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  • Barbara Marktl,

    1. Cell Biology and Plant Biochemistry, Regensburg University, Universitätsstr. 31, D-93053 Regensburg, Germany
    2. Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark
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  • Thomas Merkle,

    1. Genome Research, Faculty of Biology, University of Bielefeld, Universitätsstr. 25, D-33594 Bielefeld, Germany
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  • Gerrit T. S. Beemster,

    1. Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium
    2. Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
    3. Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
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  • Andreas Houben,

    1. Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, D-06466 Gatersleben, Germany
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  • Klaus D. Grasser

    1. Cell Biology and Plant Biochemistry, Regensburg University, Universitätsstr. 31, D-93053 Regensburg, Germany
    2. Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark
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Author for correspondence:
Klaus D. Grasser
Tel: +49 941 9433032
Email: klaus.grasser@biologie.uni-regensburg.de

Summary

  • The high mobility group (HMG)-box represents a DNA-binding domain that is found in various eukaryotic DNA-interacting proteins. Proteins that contain three copies of the HMG-box domain, termed 3 × HMG-box proteins, appear to be specific to plants. The Arabidopsis genome encodes two 3 × HMG-box proteins that were studied here.
  • DNA interactions were examined using electrophoretic mobility shift assays, whereas expression, subcellular localization and chromosome association were mainly analysed by different types of fluorescence microscopy.
  • The 3 × HMG-box proteins bind structure specifically to DNA, display DNA bending activity and, in addition to the three HMG-box domains, the basic N-terminal domain contributes to DNA binding. The expression of the two Arabidopsis genes encoding 3 × HMG-box proteins is linked to cell proliferation. In synchronized cells, expression is cell cycle dependent and peaks in cells undergoing mitosis. 3 × HMG-box proteins are excluded from the nuclei of interphase cells and localize to the cytosol, but, during mitosis, they associate with condensed chromosomes. The 3 × HMG-box2 protein generally associates with mitotic chromosomes, while 3 × HMG-box1 is detected specifically at 45S rDNA loci.
  • In addition to mitotic chromosomes the 3 × HMG-box proteins associate with meiotic chromosomes, suggesting that they are involved in a general process of chromosome function related to cell division, such as chromosome condensation and/or segregation.

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