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Insertional mutagenesis combined with an inducible filamentation phenotype reveals a conserved STE50 homologue in Cryptococcus neoformans that is required for monokaryotic fruiting and sexual reproduction

Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
Molecular Microbiology (Impact Factor: 5.03). 02/2011; 79(4):990-1007. DOI: 10.1111/j.1365-2958.2010.07501.x
Source: PubMed

ABSTRACT Cryptococcus neoformans typically grows in a yeast-like morphology; however, under specific conditions the fungus can produce hyphae that are either dikaryotic or monokaryotic. In this study, we developed a simple method for inducing robust monokaryotic fruiting and combined the assay with Agrobacterium tumefaciens insertional mutagenesis to screen for hyphal mutants. A C. neoformans homologue of the Saccharomyces cerevisiae STE50 gene was identified and characterized. STE50 was found to be required for sexual reproduction and monokaryotic fruiting. Ste50p has conserved SAM and RA domains, as well as two SH3 domains specific to basidiomycetous Ste50 proteins. Analysis of protein-protein interaction showed that Ste50p can interact with Ste11p and Ste20p, and epistasis experiments placed STE50 between STE20 and STE11. Genetic analysis of the role of STE50 in sexual reproduction showed that it was required for all steps, from response to pheromone to production of hyphae. Analysis of the effect of individual Ste50p domains on sexual reproduction and monokaryotic fruiting revealed domain-specific effects for both processes. This study revealed that the C. neoformans STE50 gene has both conserved and novel functions during sexual reproduction and monokaryotic fruiting, and these functions are domain-dependent.

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Available from: Jianmin Fu, Jan 16, 2015
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    • "Interestingly, Ste50 is also required for the production of monokaryotic hyphae during monokaryotic fruiting (Fu et al., 2011). The main role of Ste50 appears to be similar to the S. cerevisiae homologue in that it serves as an adapter protein for bringing Ste20 and Ste11 together to activate Ste11 (Fu et al., 2011). "
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