The role of yeast Hsp26 in sporulation
Date Issued
2005
Date
2005
Author(s)
Ho, Tzu-Ming
DOI
en-US
Abstract
In the budding yeast, diploid cells enter meiosis under nutrient starvation. Several heat shock proteins are induced during sporulation. The function of these heat shock proteins is unclear. In this study, we explore the role of Hsp26 in sporulation. Hsp26 is a member of the small heat shock protein superfamily. It is induced by heat shock and accumulates after diauxic shift and during the course of sporulation.
The hsp26 mutant does not decrease sporulation; instead, the sporulation frequency in the hsp26 mutant is ~20% higher than that in wild-type cells at 30℃ and ~50% higher at 32.5℃. Meiotic time course studies showed that the increase in sporulation occurs at the step of spore formation. Based on these results, we hypothesize that Hsp26 may play a spindle position checkpoint role in monitoring the distribution of daughter nuclei within the mother cells and in determining whether spore formation should proceed normally. Consistent with this hypothesis, an increase of abnormal asci, such as linear triads, is in the hsp26 mutants. In addition, when wild-type sporulating cells subjected to the reversible thermal treatment yield dyads, however, the hsp26 mutants still produced tetrads mostly. Furthermore, we have used benomyl to specifically cause spindles defects in meiotic cells. The hsp26 mutants are not affected, while the wild-type cells display a defect in sporulation. Additionally, two mutants, kar9 and dyn1, which cause misorientation of mitotic spindles were used to disturb the spindle positioning during meiosis. The results show that the sporulation defects caused by the kar9 and dyn1 mutants could be suppressed by the hsp26 mutation. Finally, the interaction between Hsp26 and Tem1 further suggests that the spindle position checkpoint is involved in our proposed checkpoint machinery. These results demonstrate that there is a novel Hsp26-dependent spindle position checkpoint to control the transition from meiosis II to spore formation.
Subjects
酵母菌
熱休克蛋白26
減數分裂
Budding yeast
Hsp26
Meiosis
Sporulation
Type
other
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