Deregulation of DSE1 Gene Expression Results in Aberrant Budding within the Birth Scar and Cell Wall Integrity Pathway Activation in Saccharomyces cerevisiae

Abstract

Strains of Saccharomyces cerevisiae lacking Isw2, the catalytic subunit of the Isw2 chromatin remodeling complex, show the mating type-independent activation of the cell wall integrity (CWI) signaling pathway. Since the CWI pathway activation usually reflects cell wall defects, we searched for the cell wall-related genes changed in expression. The genes DSE1, CTS1, and CHS1 were upregulated as a result of the absence of Isw2, according to previously published gene expression profiles (I. Frydlova, M. Basler, P. Vasicova, I. Malcova, and J. Hasek, Curr. Genet. 52:87-95, 2007). Western blot analyses of double deletion mutants, however, did not indicate the contribution of the chitin metabolism-related genes CTS1 and CHS1 to the CWI pathway activation. Nevertheless, the deletion of the DSE1 gene encoding a daughter cell-specific protein with unknown function suppressed CWI pathway activation in isw2⌬ cells. In addition, the deletion of DSE1 also abolished the budding-within-the-birth-scar phenotype of isw2⌬ cells. The plasmid-driven overexpression proved that the deregulation of Dse1 synthesis was also responsible for CWI pathway activation and manifestation of the budding-within-the-birth-scar phenotype in wild-type cells. The overproduced Dse1-green fluorescent protein localized to both sides of the septum and persisted in unbudded cells. Although the exact cellular role of this daughter cell-specific protein has to be elucidated, our data point to the involvement of Dse1 in bud site selection in haploid cells.

Cellular localization of Sun4p and its interaction with proteins in the yeast birth scar

“…1C). The deletion of the SWI5 gene caused a clear "budding within the birth scar phenotype," described previously for the isw2D strain, 9 and a more diffuse localization of Sun4p-HA in the region of the birth scar compared to wt (Figs. 1D and S2).…”

“…8 Although birth scar composition and function are rather unknown, mutants (such as isw2D or cells with Dse1p overproduction) exhibiting the "budding within the birth scar" phenotype have been isolated. 9 Daughter cell separation includes a step in which the septum is degraded from the daughter cell side by different hydrolytic enzymes [10][11][12][13] encoded by genes regulated by the Ace2p transcription factor that accumulates in daughter cell nuclei during cell division. 12 Here, we identified Sun4p, Dse2p and Dse4p as new proteins that localize to the yeast birth scar.…”

Mitotic Exit and Separation of Mother and Daughter Cells

“…Ace2 also clearly drives expression of the bud site selection gene BUD9 as well as DSE1, which may be involved in bud scar organization and bud site selection (Bidlingmaier et al 2001;Voth et al 2005;Draper et al 2009;Frydlova et al 2009). Additionally, Ace2 may promote transcription of the SUN4 glucanase (Bidlingmaier et al 2001;Di Talia et al 2009).…”

Ime1 and Ime2 Are Required for Pseudohyphal Growth of Saccharomyces cerevisiae on Nonfermentable Carbon Sources

“…To reveal more subtle differences in bud site selection, we costained cells with FITC-WGA. In addition to bud scars, FITC-WGA also stains birth scars (25). Identification of the birth scar allowed classification of budding events into events at the poles distal and proximal to the birth scar (Fig.…”

“…Cell length and width were measured using the straight tool in ImageJ. Bud and birth scars were stained as described before (25,75). Briefly, cells were grown for 18 h on SLA acetate plates and washed off plates.…”