Mating-Type-Specific Ribosomal Proteins Control Aspects of Sexual Reproduction in Cryptococcus neoformans

Giuseppe Ianiri (1) , Yufeng Francis Fang (1) , Tim A Dahlmann (2) , Shelly Applen Clancey (1) , Guilhem Janbon (3) , Ulrich Kück (2) , Joseph Heitman (1)

1 MGM - Department of Molecular Genetics and Microbiology [Durham]
2 Allgemeine und Molekulare Botanik [Bochum]
3 Biologie des ARN des Pathogènes fongiques - RNA Biology of Fungal Pathogens

The MAT locus of Cryptococcus neoformans has a bipolar organization characterized by an unusually large structure, spanning over 100 kb. MAT genes have been characterized by functional genetics as being involved in sexual reproduction and virulence. However, classical gene replacement failed to achieve mutants for five MAT genes (RPL22, RPO41, MYO2, PRT1, and RPL39), indicating that they are likely essential. In the present study, targeted gene replacement was performed in a diploid strain for both the a and a alleles of the ribosomal genes RPL22 and RPL39. Mendelian analysis of the progeny confirmed that both RPL22 and RPL39 are essential for viability. Ectopic integration of the RPL22 allele of opposite MAT identity in the heterozygous RPL22a/rpl22aD or RPL22a/ rpl22aD mutant strains failed to complement their essential phenotype. Evidence suggests that this is due to differential expression of the RPL22 genes, and an RNAi-dependent mechanism that contributes to control RPL22a expression. Furthermore, via CRISPR/Cas9 technology, the RPL22 alleles were exchanged in haploid MATa and MATa strains of C. neoformans. These RPL22 exchange strains displayed morphological and genetic defects during bilateral mating. These results contribute to elucidating functions of C. neoformans essential mating type genes that may constitute a type of imprinting system to promote inheritance of nuclei of both mating types.

Mots clés: RPL22; ribosomal genes; Cryptococcus neoformans; mating type

Domaines: Mycologie; Génétique

Giuseppe Ianiri, Yufeng Francis Fang, Tim A Dahlmann, Shelly Applen Clancey, Guilhem Janbon, et al.. Mating-Type-Specific Ribosomal Proteins Control Aspects of Sexual Reproduction in Cryptococcus neoformans. Genetics, 2020, 214 (3), pp.635-649. ⟨10.1534/genetics.119.302740⟩. ⟨pasteur-02651450⟩