Tropomyosin is required for the cell fusion process during conjugation in fission yeast

Hiroshi Kurahashi, Yoshiyuki Imai, Masayuki Yamamoto

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


Background: Tropomyosin is an actin-binding protein, which is thought to stabilize actin filaments and influence many aspects of F-actin. In fission yeast, the cdc8 gene encodes tropomyosin, and the gene product Cdc8p is known to be essential for the formation of the F-actin contractile ring and hence for cytokinesis in the mitotic cell cycle. Results: We isolated fission yeast mutants that were defective in cell fusion during conjugation. One of them turned out to carry a point mutation in cdc8. We found that the original temperature-sensitive cdc8 mutant frequently failed to undergo cell fusion when mated at a semi-permissive temperature. Additional cdc8 mutants isolated by targeted mutagenesis also showed defects in both cell fusion and cytokinesis. A decrease in the amount of intracellular Cdc8p also affected both, but cell growth was more severely blocked than cell fusion in this case. Immunostaining revealed that Cdc8p was localized as a spot at the cell-to-cell attachment site during conjugation, without overlapping with F-actin patches. Conclusions: Tropomyosin Cdc8p is indispensable for cell fusion during conjugation in fission yeast. However, cell fusion appears to require fewer tropomyosin molecules than cytokinesis. We speculate that tropomyosin may organize a small F-actin-containing organelle at the cell-to-cell contact site in each mating cell, which plays a key role in cell fusion.

Original languageEnglish
Pages (from-to)375-384
Number of pages10
JournalGenes to Cells
Issue number4
Publication statusPublished - 2002

ASJC Scopus subject areas

  • Genetics
  • Cell Biology


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