title: Real-Time Evolution of a Subtelomeric Gene Family in Candida albicans.
abstract: Subtelomeric regions of the genome are notable for high rates of sequence evolution and rapid gene turnover. Evidence of subtelomeric evolution has relied heavily on comparisons of historical evolutionary patterns to infer trends and frequencies of these events. Here, we describe evolution of the subtelomeric TLO gene family in Candida albicans during laboratory passaging for over 4000 generations. C. albicans is a commensal and opportunistic pathogen of humans and the TLO gene family encodes a subunit of the Mediator complex that regulates transcription and affects a range of virulence factors. We identified 16 distinct subtelomeric recombination events that altered the TLO repertoire. Ectopic recombination between subtelomeres on different chromosome ends occurred approximately once per 5000 generations and was often followed by loss of heterozygosity, resulting in the complete loss of one TLO gene sequence with expansion of another. In one case, recombination within TLO genes produced a novel TLO gene sequence. TLO copy number changes were biased, with some TLOs preferentially being copied to novel chromosome arms and other TLO genes being frequently lost. The majority of these nonreciprocal recombination events occurred either within the 3' end of the TLO coding sequence or within a conserved 50-bp sequence element centromere-proximal to TLO coding sequence. Thus, subtelomeric recombination is a rapid mechanism of generating genotypic diversity through alterations in the number and sequence of related gene family members.
authors.affiliation: Department of Genetics, Cell Biology and Development, University of Minnesota, Twin Cities, Minneapolis, Minnesota 55455.
authors.forename: Matthew Z
authors.initials: MZ
authors.lastname: Anderson
authors.affiliation: Department of Genetics, Cell Biology and Development, University of Minnesota, Twin Cities, Minneapolis, Minnesota 55455.
authors.forename: Lauren J
authors.initials: LJ
authors.lastname: Wigen
authors.affiliation: Department of Genetics, Cell Biology and Development, University of Minnesota, Twin Cities, Minneapolis, Minnesota 55455.
authors.forename: Laura S
authors.initials: LS
authors.lastname: Burrack
authors.affiliation: Department of Genetics, Cell Biology and Development, University of Minnesota, Twin Cities, Minneapolis, Minnesota 55455 Department of Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel judithberman11@gmail.com.
authors.forename: Judith
authors.identifier: http://orcid.org/0000-0003-0469-9819
authors.initials: J
authors.lastname: Berman
mesh_terms: D002176:Candida albicans / Q000235:genetics*; D019143:Evolution, Molecular; D005810:Multigene Family; D009154:Mutation; D011995:Recombination, Genetic; D016615:Telomere
keywords: Candida; experimental evolution; gene families; recombination; telomere