Dataset Information

Isolation and characterization of the Cryptococcus neoformans MATa pheromone gene.

ABSTRACT: Cryptococcus neoformans is a heterothallic basidiomycete with two mating types, MATa and MATalpha. The mating pathway of this fungus has a number of conserved genes, including a MATalpha-specific pheromone (MFalpha1). A modified differential display strategy was used to identify a gene encoding the MATa pheromone. The gene, designated MFa1, is 42 amino acids in length and contains a conserved farnesylation motif. MFa1 is present in three linked copies that span a 20-kb fragment of MATa-specific DNA and maps to the MAT-containing chromosome. Transformation studies showed that MFa1 induced filament formation only in MATalpha cells, demonstrating that MFa1 is functionally conserved. Sequence analysis of the predicted Mfa1 and Mfalpha1 proteins revealed that, in contrast to other fungi such as Saccharomyces cerevisiae, the C. neoformans pheromone genes are structurally and functionally conserved. However, unlike the MFalpha1 gene, which is found in MATalpha strains of both varieties of C. neoformans, MFa1 is specific for the neoformans variety of C. neoformans.

SUBMITTER: McClelland CM

PROVIDER: S-EPMC1462016 | biostudies-other | 2002 Mar

REPOSITORIES: biostudies-other

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Isolation and characterization of the Cryptococcus neoformans MATa pheromone gene.

McClelland Carol M CM Fu Jianmin J Woodlee Gay L GL Seymour Tara S TS Wickes Brian L BL

Genetics 20020301 3

Cryptococcus neoformans is a heterothallic basidiomycete with two mating types, MATa and MATalpha. The mating pathway of this fungus has a number of conserved genes, including a MATalpha-specific pheromone (MFalpha1). A modified differential display strategy was used to identify a gene encoding the MATa pheromone. The gene, designated MFa1, is 42 amino acids in length and contains a conserved farnesylation motif. MFa1 is present in three linked copies that span a 20-kb fragment of MATa-specific ...[more]

PMID: 11901112

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Project description:The fungus Cryptococcus neoformans can undergo a-? bisexual and unisexual reproduction. Completion of both sexual reproduction modes requires similar cellular differentiation processes and meiosis. Although bisexual reproduction generates equal number of a and ? progeny and is far more efficient than unisexual reproduction under mating-inducing laboratory conditions, the ? mating type dominates in nature. Population genetic studies suggest that unisexual reproduction by ? isolates might have contributed to this sharply skewed distribution of the mating types. However, the predominance of the ? mating type and the seemingly inefficient unisexual reproduction observed under laboratory conditions present a conundrum. Here, we discovered a previously unrecognized condition that promotes unisexual reproduction while suppressing bisexual reproduction. Pheromone is the principal stimulus for bisexual development in Cryptococcus. Interestingly, pheromone and other components of the pheromone pathway, including the key transcription factor Mat2, are not necessary but rather inhibitory for Cryptococcus to complete its unisexual cycle under this condition. The inactivation of the pheromone pathway promotes unisexual reproduction despite the essential role of this pathway in non-self-recognition during bisexual reproduction. Nonetheless, the requirement for the known filamentation regulator Znf2 and the expression of hyphal or basidium specific proteins remain the same for pheromone-dependent or independent sexual reproduction. Transcriptome analyses and an insertional mutagenesis screen in mat2? identified calcineurin being essential for this process. We further found that Znf2 and calcineurin work cooperatively in controlling unisexual development in this fungus. These findings indicate that Mat2 acts as a repressor of pheromone-independent unisexual development while serving as an activator for a-? bisexual development. The bi-functionality of Mat2 might have allowed it to act as a toggle switch for the mode of sexual development in this ubiquitous eukaryotic microbe.

Dataset Information

Isolation and characterization of the Cryptococcus neoformans MATa pheromone gene.

Publications

Isolation and characterization of the Cryptococcus neoformans MATa pheromone gene.

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