Dataset Information

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

ABSTRACT: 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 ? 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 RPL22 a/rpl22?? or RPL22?/rpl22 a? 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 RPL22 a expression. Furthermore, via CRISPR/Cas9 technology, the RPL22 alleles were exchanged in haploid MAT? and MAT a 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.

SUBMITTER: Ianiri G

PROVIDER: S-EPMC7054023 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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

Ianiri Giuseppe G Fang Yufeng Francis YF Dahlmann Tim A TA Clancey Shelly Applen SA Janbon Guilhem G Kück Ulrich U Heitman Joseph J

Genetics 20191227 3

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, ta ...[more]

PMID: 31882399

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Project description:Meiotic recombination of sex chromosomes is thought to be repressed in organisms with heterogametic sex determination (e.g. mammalian X/Y chromosomes), due to extensive divergence and chromosomal rearrangements between the two chromosomes. However, proper segregation of sex chromosomes during meiosis requires crossing-over occurring within the pseudoautosomal regions (PAR). Recent studies reveal that recombination, in the form of gene conversion, is widely distributed within and may have played important roles in the evolution of some chromosomal regions within which recombination was thought to be repressed, such as the centromere cores of maize. Cryptococcus neoformans, a major human pathogenic fungus, has an unusually large mating-type locus (MAT, >100 kb), and the MAT alleles from the two opposite mating-types show extensive nucleotide sequence divergence and chromosomal rearrangements, mirroring characteristics of sex chromosomes. Meiotic recombination was assumed to be repressed within the C. neoformans MAT locus. A previous study identified recombination hot spots flanking the C. neoformans MAT, and these hot spots are associated with high GC content. Here, we investigated a GC-rich intergenic region located within the MAT locus of C. neoformans to establish if this region also exhibits unique recombination behavior during meiosis. Population genetics analysis of natural C. neoformans isolates revealed signals of homogenization spanning this GC-rich intergenic region within different C. neoformans lineages, consistent with a model in which gene conversion of this region during meiosis prevents it from diversifying within each lineage. By analyzing meiotic progeny from laboratory crosses, we found that meiotic recombination (gene conversion) occurs around the GC-rich intergenic region at a frequency equal to or greater than the meiotic recombination frequency observed in other genomic regions. We discuss the implications of these findings with regards to the possible functional and evolutionary importance of gene conversion within the C. neoformans MAT locus and, more generally, in fungi.

Dataset Information

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

Publications

Mating-Type-Specific Ribosomal Proteins Control Aspects of Sexual Reproduction in <i>Cryptococcus neoformans</i>.

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