Hall AE, Rose MD

During mating, S. cerevisiae cells must degrade the intervening cell wall to allow fusion of the partners. Because improper timing or location of cell wall degradation would cause lysis, the initiation of cell fusion must be highly regulated. Here, we find that yeast cell fusion is negatively regulated by components ...

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of the Cell Wall Integrity (CWI) pathway. Loss of the cell wall sensor, MID2, specifically causes "mating-induced death" after pheromone exposure. Mating-induced death is suppressed by mutations in cell fusion genes ( FUS1, FUS2, RVS161, CDC42), implying that mid2Δ cells die from premature fusion without a partner. Consistent with premature fusion, mid2Δ shmoos had thinner cell walls and lysed at the shmoo tip. Normally, Cdc42p co-localizes with Fus2p to form a focus only when mating cells are in contact (prezygotes) and co-localization is required for cell fusion. However, Cdc42p was aberrantly co-localized with Fus2p to form a focus in mid2Δ shmoos. A hyperactive allele of the CWI kinase Pkc1p ( PKC1*) caused decreased cell fusion and Cdc42p localization in prezygotes. In shmoos, PKC1* increased Cdc42p localization, however it was not co-localized with Fus2p or associated with cell death. We conclude that Mid2p and Pkc1p negatively regulate cell fusion via Cdc42p and Fus2p.

Date: Dec. 26, 2018

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