Diverse Hap43-independent functions of the Candida albicans CCAAT-binding complex.
Eukaryot Cell, 2013/6;12(6):804-15.
Hsu PC[1], Chao CC, Yang CY, Ye YL, Liu FC, Chuang YJ, Lan CY
Affiliations
PMID: 23543673DOI: 10.1128/EC.00014-13
Abstract
The CCAAT motif is ubiquitous in promoters of eukaryotic genomes. The CCAAT-binding complex (CBC) is conserved across a wide range of organisms, specifically recognizes the CCAAT motif, and modulates transcription directly or in cooperation with other transcription factors. In Candida albicans, CBC is known to interact with the repressor Hap43 to negatively regulate iron utilization genes in response to iron deprivation. However, the extent of additional functions of CBC is unclear. In this study, we explored new roles of CBC in C. albicans and found that CBC pleiotropically regulates many virulence traits in vitro, including negative control of genes responsible for ribosome biogenesis and translation and positive regulation of low-nitrogen-induced filamentation. In addition, C. albicans CBC is involved in utilization of host proteins as nitrogen sources and in repression of cellular flocculation and adhesin gene expression. Moreover, our epistasis analyses suggest that CBC acts as a downstream effector of Rhb1-TOR signaling and controls low-nitrogen-induced filamentation via the Mep2-Ras1-protein kinase A (PKA)/mitogen-activated protein kinase (MAPK) pathway. Importantly, the phenotypes identified here are all independent of Hap43. Finally, deletion of genes encoding CBC components slightly attenuated C. albicans virulence in both zebrafish and murine models of infection. Our results thus highlight new roles of C. albicans CBC in regulating multiple virulence traits in response to environmental perturbations and, finally, suggest potential targets for antifungal therapies as well as extending our understanding of the pathogenesis of other fungal pathogens.
MeSH terms
Animals; CCAAT-Binding Factor; Candida albicans; Candidiasis; Cation Transport Proteins; Fungal Proteins; GTP Phosphohydrolases; Gene Expression Regulation, Fungal; Iron; Mice; Mitogen-Activated Protein Kinases; Mutation; Promoter Regions, Genetic; Repressor Proteins; Signal Transduction; Survival Analysis; TOR Serine-Threonine Kinases; Virulence; Zebrafish; ras Proteins
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