Deletion of a Yci1 Domain Protein of Candida albicans Allows Homothallic Mating in MTL Heterozygous Cells

Abstract

It has been proposed that the ancestral fungus was mating competent and homothallic. However, many mating-competent fungi were initially classified as asexual because their mating capacity was hidden behind layers of regulation. For efficient in vitro mating, the essentially obligate diploid ascomycete pathogen Candida albicans has to change its mating type locus from heterozygous MTLa/α to homozygous MTLa/a or MTLα/α and then undergo an environmentally controlled epigenetic switch to the mating-competent opaque form. These requirements greatly reduce the potential for C. albicans mating. Deletion of the Yci1 domain gene OFR1 bypasses the need for C. albicans cells to change the mating type locus from heterozygous to homozygous prior to switching to the opaque form and mating and allows homothallic mating of MTL heterozygous strains. This bypass is carbon source dependent and does not occur when cells are grown on glucose. Transcriptional profiling of ofr1 mutant cells shows that in addition to regulating cell type and mating circuitry, Ofr1 is needed for proper regulation of histone and chitin biosynthesis gene expression. It appears that OFR1 is a key regulator in C. albicans and functions in part to maintain the cryptic mating phenotype of the pathogen.

High Throughput Yeast Strain Phenotyping with Droplet-Based RNA Sequencing

“…In clusters 0 and 2, WH11 and STF2 were significantly downregulated compared with cluster 1 (Figure 4D). Genes involved in fermentation, such as ADH1, were upregulated in cluster 0, consistent with previous studies of opaque cells 22 .…”

RNA sequencing reveals an additional Crz1-binding motif in promoters of its target genes in the human fungal pathogen Candida albicans

“…RNA-seq libraries were constructed using Illumina's miSEQ RNA Sample Preparation Kit (Illumina Inc., USA). RNA sequencing, data analysis and sequence assembly were performed by the Quebec Genome Innovation Center at McGill University (Montreal, Canada) [31,38]. Preparation of the paired-end libraries and sequencing were performed following standard Illumina methods and protocols.…”

Environment-induced same-sex mating in the yeast Candida albicans through the Hsf1–Hsp90 pathway

“…Inactivation of the Bar1 protease or the Dipeptidyl aminopeptidase YC1 (Yci1) domain protein Opaque Formation Regulator 1 (Ofr1) has been shown to induce same-sex mating in C . albicans [ 16 , 44 ]. We observed that BAR1 was not down-regulated but rather highly induced upon glucose starvation ( Fig 1 ).…”