Mub1 protein regulates mating differentiation and yeast cell morphogenesis in Cryptococcus neoformans
Date Issued
2012
Date
2012
Author(s)
Sun, Wei-Lun
Abstract
Cryptococcus neoformans is a heterothallic basidiomycete that grows vegetatively as yeast cells and produces mating filaments in the sexual state. Mating initiates when MATa and MATα cells conjugate and fuse, and then dikaryotic sexual filaments are subsequently produced. Generation of final fruiting structures basidia and meiotic progeny basidiospores leads to completion of the sexual cycle. Prior studies have revealed that C. neoformans Cwc1 and Cwc2 proteins are two central photoregulators which form a complex to inhibit the production of sexual filaments upon blue light irradiation. To reveal the detailed light response networks, a genome wide mutagenesis screen was conducted and components involved in light-mediated filamentation pathway have been identified. In this study, a suppressor mutant EE24 was characterized and T-DNA was found to insert at the upstream regulatory region of C. neoformans MUB1 gene, a homologue of Saccharomyces cerevisiae MUB1 (multi-budding) gene. In S. cerevisiae, Mub1p is a MYND domain-containing protein required for ubiquitination and turnover of Rpn4p, a transcription factor of proteasome genes. Deletion of C. neoformans MUB1 gene caused compromised growth at 37°C. C. neoformans mub1 mutants similarly displayed a multiple-budding phenotype and altered structures of bud scars were observed. Furthermore, morphogenesis of dikaryotic sexual filaments and generation of basidiospores were defective in the mub1 bilateral cross. Interestingly, early stages of same sex mating was negatively regulated by Mub1. Our studies demonstrate that C. neoformans MUB1 is an important gene that regulates yeast cell morphogenesis and mating differentiation.
Subjects
Cryptococcus neoformans
Multi-budding
Same sex mating
Cell Morphogenesis
mating
Light response
Type
thesis
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