The tetraspan protein Dni1p is required for correct membrane organization and cell wall remodelling during mating in Schizosaccharomyces pombe

Authors

  • José Ángel Clemente-Ramos,

    1. Departamento de Microbiología y Genética/Instituto de Microbiología Bioquímica, Universidad de Salamanca/CSIC, Edificio Departamental, Campus Miguel de Unamuno, 37007-Salamanca, Spain.
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    • These author contributed equally to the development of this work.

  • Rebeca Martín-García,

    1. Departamento de Microbiología y Genética/Instituto de Microbiología Bioquímica, Universidad de Salamanca/CSIC, Edificio Departamental, Campus Miguel de Unamuno, 37007-Salamanca, Spain.
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    • These author contributed equally to the development of this work.

  • Mohammad R. Sharifmoghadam,

    1. Departamento de Microbiología y Genética/Instituto de Microbiología Bioquímica, Universidad de Salamanca/CSIC, Edificio Departamental, Campus Miguel de Unamuno, 37007-Salamanca, Spain.
    2. Faculty of Veterinary Medicine, Zabol University, Zabol, Iran.
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    • These author contributed equally to the development of this work.

  • Mami Konomi,

    1. Laboratory of Electron Microscopy/Open Research Centre and
    2. Department of Chemical and Biological Sciences, Japan Women's University, 2-8-1, Mejirodai, Bunkyo-ku, Tokyo 112-8681, Japan.
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  • Masako Osumi,

    1. Department of Chemical and Biological Sciences, Japan Women's University, 2-8-1, Mejirodai, Bunkyo-ku, Tokyo 112-8681, Japan.
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  • M.-Henar Valdivieso

    Corresponding author
    1. Departamento de Microbiología y Genética/Instituto de Microbiología Bioquímica, Universidad de Salamanca/CSIC, Edificio Departamental, Campus Miguel de Unamuno, 37007-Salamanca, Spain.
      *E-mail henar@usal.es; Tel. (+34) 923 121589; Fax (+34) 923 224876.
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*E-mail henar@usal.es; Tel. (+34) 923 121589; Fax (+34) 923 224876.

Summary

In fungi, success of mating requires that both cells agglutinate, modify their extracellular envelopes, and fuse their plasma membranes and nuclei to produce a zygote. Here we studied the role of the Schizosaccharomyces pombe Dni1 protein in the cell fusion step of mating. Dni1p is a tetraspan protein bearing a conserved cystein motif similar to that present in fungal claudin-related proteins. Dni1p expression is induced during mating and Dni1p concentrates as discrete patches at the cell–cell contact area and along the mating bridge. Proper Dni1p localization depends on Fus1p, actin and integrity of lipid rafts. In dni1Δ mutants, cell differentiation and agglutination are as efficient as in the wild-type strain, but cell fusion is significantly reduced at temperatures above 25°C. We found that the defect in cell fusion was not associated with an altered cytoskeleton, with an abnormal distribution of Fus1p, or with a defect in calcium accumulation, but with a severe disorganization of the plasma membrane and cell wall at the area of cell–cell contact. These results show that Dni1p plays a relevant role in co-ordinating membrane organization and cell wall remodelling during mating, a function that has not been described for other proteins in the fission yeast.

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