Open AccessA single Ho-induced double-strand break at the MAT locus is lethal in Candida glabrata
Author(s) -
Laetitia Maroc,
Youfang Zhou-Li,
Stéphanie Boisnard,
Cécile Fairhead
Publication year - 2020
Publication title -
plos genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.587
H-Index - 233
eISSN - 1553-7404
pISSN - 1553-7390
DOI - 10.1371/journal.pgen.1008627
Subject(s) - biology , mating type , mating of yeast , saccharomyces cerevisiae , candida glabrata , locus (genetics) , genetics , homologous recombination , mating , wild type , recombination , yeast , gene , microbiology and biotechnology , candida albicans , mutant
Mating-type switching is a complex mechanism that promotes sexual reproduction in Saccharomycotina. In the model species Saccharomyces cerevisiae , mating-type switching is initiated by the Ho endonuclease that performs a site-specific double-strand break (DSB) at MAT , repaired by homologous recombination (HR) using one of the two silent mating-type loci, HMLalpha and HMRa . The reasons why all the elements of the mating-type switching system have been conserved in some Saccharomycotina, that do not show a sexual cycle nor mating-type switching, remain unknown. To gain insight on this phenomenon, we used the yeast Candida glabrata , phylogenetically close to S . cerevisiae , and for which no spontaneous and efficient mating-type switching has been observed. We have previously shown that expression of S . cerevisiae ’s Ho ( Sc Ho) gene triggers mating-type switching in C . glabrata , but this leads to massive cell death. In addition, we unexpectedly found, that not only MAT but also HML was cut in this species, suggesting the formation of multiple chromosomal DSBs upon HO induction. We now report that HMR is also cut by Sc Ho in wild-type strains of C . glabrata . To understand the link between mating-type switching and cell death in C . glabrata , we constructed strains mutated precisely at the Ho recognition sites. We find that even when HML and HMR are protected from the Ho-cut, introducing a DSB at MAT is sufficient to induce cell death, whereas one DSB at HML or HMR is not. We demonstrate that mating-type switching in C . glabrata can be triggered using CRISPR-Cas9, without high lethality. We also show that switching is Rad51-dependent, as in S . cerevisiae , but that donor preference is not conserved in C . glabrata . Altogether, these results suggest that a DSB at MAT can be repaired by HR in C . glabrata , but that repair is prevented by Sc Ho.