Pob1 Ensures Cylindrical Cell Shape by Coupling Two Distinct Rho Signaling Events During Secretory Vesicle Targeting

Authors

  • Kentaro Nakano,

    Corresponding author
    1. Department of Structural Biosciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
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  • Mika Toya,

    1. Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo, Tokyo 113-0033, Japan
    2. Laboratory for Developmental Genomics, RIKEN Center for Developmental Biology, Kobe 658-0081, Japan
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  • Aki Yoneda,

    1. Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University, Tokyo 112-0015, Japan
    2. Department of Biology, Washington University, Saint Louis, MO 63130, USA
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  • Yukiko Asami,

    1. Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University, Tokyo 112-0015, Japan
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  • Akira Yamashita,

    1. Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo, Tokyo 113-0033, Japan
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  • Naomi Kamasawa,

    1. Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University, Tokyo 112-0015, Japan
    2. Division of Cerebral structure, National Institute of Physiological Science, Myodaiji, Okazaki 444-8787, Japan
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  • Masako Osumi,

    1. Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University, Tokyo 112-0015, Japan
    2. Integrated Imaging Research Support, Hirakawacho, Chiyoda-ku, Tokyo 102-0093, Japan
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  • Masayuki Yamamoto

    1. Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo, Tokyo 113-0033, Japan
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Kentaro Nakano, knakano@biol.tsukuba.ac.jp

Abstract

Proper cell morphogenesis requires the co-ordination of cell polarity, cytoskeletal organization and vesicle trafficking. The Schizosaccharomyces pombe mutant pob1-664 has a curious lemon-like shape, the basis of which is not understood. Here, we found abundant vesicle accumulation in these cells, suggesting that Pob1 plays a role in vesicle trafficking. We identified Rho3 as a multicopy suppressor of this phenotype. Because Rho3 function is related to For3, an actin-polymerizing protein, and Sec8, a component of the exocyst complex, we analyzed their functional relationship with Pob1. Pob1 was essential for the formation of actin cables (by interacting with For3) and for the polarized localization of Sec8. Although neither For3 nor Sec8 is essential for polarized growth, their simultaneous disruption prevented tip growth and yielded a lemon-like cell morphology similar to pob1-664. Thus, Pob1 may ensure cylindrical cell shape of S. pombe by coupling actin-mediated vesicle transport and exocyst-mediated vesicle tethering during secretory vesicle targeting.

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