Telomeric ORFS in Candida albicans: does mediator tail wag the yeast?

Abstract

Recent studies of fungal genomes have shown that subtelomeric regions of chromosomes are areas of rapid evolution that facilitate adaptation to novel niches [1]. Several years ago, analysis of the genome of the human pathogenic yeast Candida albicans revealed the presence of a large family of telomeric orfs (TLO genes) [2]. The function of this gene family remained an enigma in C. albicans genetics for many years; however, recent studies have revealed that the TLO genes encode a subunit of the Mediator complex with roles in transcriptional regulation [3,4]. This gene family expansion is unique to C. albicans, the species responsible for the majority of human yeast infections and the species that is most commonly recovered as a human commensal. If selective pressures in the host have driven this expansion, it is likely that this gene family somehow contributes to the success of C. albicans as a commensal and opportunistic pathogen. To support this hypothesis, it was first necessary to determine the exact function of Tlo proteins in C. albicans. Armed with this knowledge, investigators are now beginning to understand how possession of multiple copies of TLO could contribute to the virulence properties of C. albicans.