Role of phosphatidylinositol 3-phosphate in formation of forespore membrane in Schizosaccharomyces pombe

Masayuki Onishi, Takako Koga, Rika Morita, Yoko Nakamura, Taro Nakamura, Chikashi Shimoda, Kaoru Takegawa, Aiko Hirata, Yasuhisa Fukui

Research output: Contribution to journalReview articlepeer-review

21 Citations (Scopus)


Phosphatidylinositol (PI) 3-kinase (encoded by the pik3+ gene) in Schizosaccharomyces pombe has been identified as a homologue of VPS34p, a protein required for proper vesicular protein sorting. The clone defective in this protein carries enlarged vacuoles and exhibits sensitivity to high temperature or high ion concentration. The effect of disruption of pik3+ on sporulation of Sz. pombe was examined. The diploid cells underwent G1 arrest and meiosis. However, the spores formed by the Δpik3 cells were not viable. Electron-microscopic analysis revealed that the growth of the forespore membrane of Δpik3 cells was not correctly orientated, failing to engulf the nucleus or forming extremely small spores, as was confirmed by the use of Spo3p-GFP and GFP-Psy1p, which are markers of the forespore membrane. The coating materials found along the forespore membrane of the wild-type were greatly reduced in these cells. PI 3-P, the product of Pik3p, was detected on the forespore membrane, suggesting that PI 3-P-dependent vesicle transport may take place in formation of the forespore membrane. Misshaped forespore membrane, accumulation of vesicles, formation of small non-viable spores, and suppression by over expression of Psy1p were the phenotypes commonly seen in Δpik3 and Δspo3 cells, suggesting a relationship between the functions of Pik3p and Spo3p in formation of the forespore membrane in Sz. pombe.

Original languageEnglish
Pages (from-to)193-206
Number of pages14
Issue number3
Publication statusPublished - Feb 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Bioengineering
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Genetics


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