The mating type-like loci of Candida glabrata / Los loci de apareamiento de Candida glabrata

Candida glabrata, a haploid and opportunistic fungal pathogen that has not known sexual cycle, has conserved the majority of the genes required for mating and cell type identity. The C. glabrata genome contains three mating-type-like loci called MTL1, MTL2 and MTL3. The three loci encode putative transcription factors, a1, α1 and α2 that regulate cell type identity and sexual reproduction in other fungi like the closely related Saccharomyces cerevisiae. MTL1 can contain either a or α information. MTL2, which contains a information and MTL3 with α information, are relatively close to two telomeres. MTL1 and MTL2 are transcriptionally active, while MTL3 is subject to an incomplete silencing nucleated at the telomere that depends on the silencing proteins Sir2, Sir3, Sir4, yKu70/80, Rif1, Rap1 and Sum1. C. glabrata does not seem to maintain cell type identity, as cell type-specific genes are expressed regardless of the type (or even absence) of mating information. These data highlight important differences in the control of mating and cell type identity between the non-pathogenic yeast S. cerevisiae and C. glabrata, which might explain the absence of a sexual cycle in C. glabrata. The fact that C. glabrata has conserved the vast majority of the genes involved in mating might suggest that some of these genes perhaps have been rewired to control other processes important for the survival inside the host as a commensal or as a human pathogen. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012) (AU)

Candida glabrata, una levadura patógena haploide y oportunista, que carece de ciclo sexual conocido (asexual), conserva la mayoría de genes ortólogos requeridos en los procesos de apareamiento, esporulación y la identidad del tipo celular. El genoma de C. glabrata contiene 3 loci de apareamiento llamados MTL1, MTL2 y MTL3 que codifican los presuntos factores de transcripción a1, α1 y α2 que controlan la reproducción sexual e identidad celular en otros hongos, como Saccharomyces cerevisiae con el cual tiene una estrecha relación filogenética. MTL1 puede contener información a o α; MTL2 contiene información a, y MTL3 que contiene información α1 y α2 son loci próximos a 2 telómeros. MTL1 y MTL2 son activos transcripcionalmente mientras que MTL3 está sujeto a un silenciamiento que no es completo, que proviene del telómero y depende de las proteínas Sir2, Sir3, Sir4, yKu70/80, Rif1, Rap1 y Sum1. C. glabrata parece no mantener identidad de tipo celular ya que varios genes específicos de un tipo celular se expresan en todas las células con independencia del tipo de información de apareamiento en los loci MTL, o incluso, en su ausencia. Estos datos ilustran varias diferencias importantes entre la levadura no patógena S. cerevisiae y C. glabrata que podrían explicar la característica asexual en esta última. El hecho de que en C. glabrata se hayan conservado los genes necesarios para el apareamiento podría indicar que es posible que algunos de estos genes se hayan «reorganizado» para controlar otros procesos importantes en la supervivencia de C. glabrata en su huésped, como comensal o como patógeno.Este artículo forma parte de una serie de estudios presentados en el «V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi» (Oaxaca, México, 2012) (AU)

The mating type-like loci of Candida glabrata.

Candida glabrata, a haploid and opportunistic fungal pathogen that has not known sexual cycle, has conserved the majority of the genes required for mating and cell type identity. The C. glabrata genome contains three mating-type-like loci called MTL1, MTL2 and MTL3. The three loci encode putative transcription factors, a1, α1 and α2 that regulate cell type identity and sexual reproduction in other fungi like the closely related Saccharomyces cerevisiae. MTL1 can contain either a or α information. MTL2, which contains a information and MTL3 with α information, are relatively close to two telomeres. MTL1 and MTL2 are transcriptionally active, while MTL3 is subject to an incomplete silencing nucleated at the telomere that depends on the silencing proteins Sir2, Sir3, Sir4, yKu70/80, Rif1, Rap1 and Sum1. C. glabrata does not seem to maintain cell type identity, as cell type-specific genes are expressed regardless of the type (or even absence) of mating information. These data highlight important differences in the control of mating and cell type identity between the non-pathogenic yeast S. cerevisiae and C. glabrata, which might explain the absence of a sexual cycle in C. glabrata. The fact that C. glabrata has conserved the vast majority of the genes involved in mating might suggest that some of these genes perhaps have been rewired to control other processes important for the survival inside the host as a commensal or as a human pathogen. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012).