A starvation-specific serine protease gene, isp6+, is involved in both autophagy and sexual development in Schizosaccharomyces pombe.
Schizosaccharomyces pombe isp6(+) gene encodes a vacuolar serine protease, which is specifically induced during nitrogen starvation. An isp6-disruption mutant, isp6Delta, grew normally under normal conditions but was defective in large-scale protein degradation during nitrogen starvation, a hallmark of autophagy. Vacuoles are the organelles for such drastic protein degradation but those of isp6Delta were apparently aberrant. isp6Delta was infertile under nitrogen source-free conditions with poor expression of ste11(+), a gene critical for sexual development. A protein kinase A-disruption mutant, pka1Delta, is prone to sexual development because expression of ste11(+) is derepressed. However, isp6Deltapka1Delta still showed defects in ste11(+) expression and sexual development under nitrogen source-free conditions. isp6Delta and isp6Deltapka1Delta were able to initiate sexual development to produce spores when only a small amount of a nitrogen source was present. Pat1 protein kinase negatively controls meiosis, and a temperature-sensitive mutant of pat1, pat1-114, initiates meiosis irrespective of ploidy at the restrictive temperature. However, isp6Deltapat1-114 did not start meiosis under nitrogen source-free conditions even at the restrictive temperature. These observations suggest that isp6(+) contributes to sexual development by providing a nitrogen source through autophagy.
Nakashima
Akio
A
Department of Chemistry, Faculty of Science, Shizuoka University, 836 Oya, 422-8539, Shizuoka, Japan.
Hasegawa
Takahiro
T
Mori
Saori
S
Ueno
Masaru
M
Tanaka
Shigeyasu
S
Ushimaru
Takashi
T
Sato
Shusei
S
Uritani
Masahiro
M
D001343:Autophagy / Q000235:genetics / Q000502:physiology*; D004843:Epistasis, Genetic; D015966:Gene Expression Regulation, Fungal; D008540:Meiosis; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000172:deficiency / Q000378:metabolism; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors
D008565:Membrane Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C489968:isp6 protein, S pombe; C071596:ste11 protein, S pombe; D012697:Serine Endopeptidases; D009584:Nitrogen