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Updated: Mar 23, 2026
Automated Measurement of Cryptococcal Species Polysaccharide Capsule and Cell Body
Published on: January 11, 2018
Morphotype-specific effector functions of Cryptococcus neoformans PUM1
Jan Naseer Kaur1, John C Panepinto1
1Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, the State University of New York., USA.
Abstract:
The basidiomycete fungal pathogen Cryptococcus neoformans requires the PUF protein, Pum1, for hyphal morphogenesis during sexual development. In this study we found that Pum1 was auto-repressive under growth as yeast, but that auto-repression was relieved during filamentous growth through utilization of an alternative transcription start site driven by the master filamentation regulator Znf2. In addition, Pum1 was required to stabilize the ZNF2 mRNA through an indirect mechanism suggesting that Znf2 and Pum1 each positively regulate the expression of the other to achieve the filamentous morphotype required for sexual development in Cryptococcus.
Insights
The fungal pathogen Cryptococcus neoformans uses Pum1 protein for filament formation. Znf2 protein triggers Pum1
Area of Science:
- Mycology
- Molecular Biology
- Genetics
Background:
- Cryptococcus neoformans is a fungal pathogen that undergoes sexual development involving hyphal morphogenesis.
- The PUF protein family, including Pum1, plays critical roles in post-transcriptional gene regulation in eukaryotes.
- Hyphal development in C. neoformans is essential for its sexual cycle and pathogenesis.
Purpose of the Study:
- To investigate the role of the Pum1 protein in hyphal morphogenesis during sexual development in Cryptococcus neoformans.
- To elucidate the regulatory mechanisms controlling Pum1 expression and its interaction with other developmental regulators.
- To understand the interplay between Pum1 and Znf2 in achieving the filamentous morphotype.
Main Methods:
- Analysis of Pum1 auto-repression under different growth conditions (yeast vs. filamentous).
- Identification of alternative transcription start sites for Pum1.
- Investigation of the role of the Znf2 regulator in controlling Pum1 transcription.
- Assessment of Pum1's effect on ZNF2 mRNA stability.
Main Results:
- Pum1 exhibits auto-repression during yeast growth, which is alleviated during filamentous growth.
- Filamentous growth involves an alternative transcription start site for Pum1, regulated by Znf2.
- Pum1 indirectly stabilizes ZNF2 mRNA, suggesting a positive feedback loop.
- Znf2 and Pum1 positively regulate each other's expression to promote filamentous growth.
Conclusions:
- The study reveals a novel regulatory mechanism for hyphal morphogenesis in Cryptococcus neoformans involving Pum1 and Znf2.
- A reciprocal positive regulatory loop between Pum1 and Znf2 is crucial for achieving the filamentous morphotype necessary for sexual development.
- Understanding this pathway provides insights into fungal development and potential targets for antifungal strategies.
