Poster: 107 - Print

Epistatic Analysis of Candida albicans Yck2Δ/Δ Mutant Strain: Implications of Gene Expression Profile on Mutant Morphology and Stress Response

Authors

Abstract

Morphology transition from yeast to hyphae is a key virulence trait in Candida albicans and is tightly regulated in response to environmental signals. Yeast casein kinase 2 (YCK2), a member of the casein kinase 1 (CK1) family of serine/threonine kinases, is known to play a key role in governing morphogenesis, host cell damage, and stress response in C.albicans. The yck2 deletion mutant strain (yck2 Δ/Δ) has shown severe phenotypic defects including slower growth in YPD and glucose, cell wall defects, formation of pseudohyphae, significantly reduced damage to endothelial and epithelial cells, and increased susceptibility to cell wall stressors compared to wild type and YCK2 complement strains. In order to identify genes that contribute to the observed yck2 Δ/Δ mutant phenotype and select potential downstream genes that may be transcriptionally regulated by YCK2 for future study, a gene expression profile for each strain was generated using qRT-PCR. Transcript levels of 16 key genes in yck2Δ/Δ were compared relative to WT and yck2 complement (Rev) strains in both yeast and induced hyphae form. Yeast expression data shows increased expression of UME6; likely responsible for observed pseudohyphal growth in the yck2Δ/Δ strain, and RGT2, HGT7 and HXT10; all glucose transporter genes involved in glucose sensing pathway, potentially as a compensatory response. Underexpression of cell integrity genes HOG1 and MKC1 is consistent with observed lowered resistance to cell wall stressors in the yck2 Δ/Δ strain. SSD1 did not show significant change of expression in the absence of YCK2, suggesting that it is controlled by an alternate pathway.

Keywords

epistatic analysis, transcription profile, candida albicans