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Casein kinase 1γ acts as a molecular switch for cell polarization through phosphorylation of the polarity factor T ea1 in fission yeast
Author(s) -
Koyano Takayuki,
Barnouin Karin,
Snijders Ambrosius P.,
Kume Kazunori,
Hirata Dai,
Toda Takashi
Publication year - 2015
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/gtc.12309
Subject(s) - biology , phosphoserine , phosphorylation , microbiology and biotechnology , casein kinase 2 , kinase , schizosaccharomyces pombe , casein kinase 1 , serine , cyclin dependent kinase 1 , protein kinase a , hyperphosphorylation , cell cycle , cell growth , cell , cyclin dependent kinase 2 , yeast , biochemistry , saccharomyces cerevisiae
Fission yeast undergoes growth polarity transition from monopolar to bipolar during G 2 phase, designated NETO (New End Take Off). It is known that NETO onset involves two prerequisites, the completion of DNA replication and attainment of a certain cell size. However, the molecular mechanism remains unexplored. Here, we show that casein kinase 1γ, C ki3 is a critical determinant of NETO onset. Not only did cki3 ∆ cells undergo NETO during G 1‐ or S ‐phase, but they also displayed premature NETO under unperturbed conditions with a smaller cell size, leading to cell integrity defects. C ki3 interacted with the polarity factor Tea1, of which phosphorylation was dependent on C ki3 kinase activity. GFP nanotrap of T ea1 by C ki3 led to T ea1 hyperphosphorylation with monopolar growth, whereas the same entrapment by kinase‐dead C ki3 resulted in converse bipolar growth. Intriguingly, the T ea1 interactor T ea4 was dissociated from T ea1 by C ki3 entrapment. Mass spectrometry identified four phosphoserine residues within T ea1 that were hypophosphorylated in cki3 ∆ cells. Phosphomimetic T ea1 mutants showed compromised binding to T ea4 and NETO defects, indicating that these serine residues are critical for protein–protein interaction and NETO onset. Our findings provide significant insight into the mechanism by which cell polarization is regulated in a spatiotemporal manner.