Development of ptxD/Phi as a new dominant selection system for genetic manipulation in Cryptococcus neoformans

ABSTRACT Cryptococcus neoformans is a globally distributed pathogenic fungus posing a significant threat to immunocompromised individuals, particularly those with HIV/AIDS. Effective genetic manipulation tools are essential for understanding its biology and developing new therapies. However, current...

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Main Authors: Muthita Khongthongdam, Tanaporn Phetruen, Sittinan Chanarat
Format: Article
Language:English
Published: American Society for Microbiology 2025-01-01
Series:Microbiology Spectrum
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Online Access:https://journals.asm.org/doi/10.1128/spectrum.01618-24
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author Muthita Khongthongdam
Tanaporn Phetruen
Sittinan Chanarat
author_facet Muthita Khongthongdam
Tanaporn Phetruen
Sittinan Chanarat
author_sort Muthita Khongthongdam
collection DOAJ
description ABSTRACT Cryptococcus neoformans is a globally distributed pathogenic fungus posing a significant threat to immunocompromised individuals, particularly those with HIV/AIDS. Effective genetic manipulation tools are essential for understanding its biology and developing new therapies. However, current genetic tools, including the variation of versatile selectable markers, are limited. This study develops and validates the phosphite dehydrogenase gene (ptxD)/phosphite (Phi) selection system as a non-antibiotic selectable marker for genetic manipulation in C. neoformans. A codon-optimized ptxD gene from Pseudomonas stutzeri was cloned under the TEF promoter. Using the transient CRISPR-Cas9 coupled with electroporation system, we integrated the ptxD gene into the C. neoformans genome and assessed the impact of ptxD integration on cell growth and virulence factors. The ptxD/Phi system effectively selected transformed cells on Phi-containing media. Growth assays showed that ptxD integration did not adversely affect cell growth or key virulence factors, including pleomorphism, capsule size, and melanin production. Additionally, we successfully disrupted the ADE2 gene using this system, confirming its applicability for gene deletion. Taken together, the ptxD/Phi system provides a robust and versatile tool for genetic manipulation in C. neoformans, facilitating further research into its biology and pathogenicity.IMPORTANCECryptococcus neoformans is a type of fungus that can cause serious illnesses in people who have weakened immune systems, like those with HIV/AIDS. To better study this fungus and find new treatments, scientists need tools to change its genes in precise ways. However, the current tools available for this are somewhat limited. This research introduces a new tool called the phosphite dehydrogenase gene/phosphite system, which does not rely on antibiotics to work. It uses a gene from a different bacterium that helps select and grow only the fungus cells that have successfully incorporated new genetic information. This is particularly useful because it does not interfere with the normal growth of the fungus or the features that make it harmful (like its ability to change shape or produce protective coatings). By making it easier and more effective to manipulate the genetics of C. neoformans, this tool opens up new possibilities for understanding how this fungus operates and for developing therapies to combat its infections. This is crucial for improving the treatment of infections in vulnerable populations.
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spelling doaj-art-8bd6cd0f043a46dca2c64a0f608aee312025-01-07T14:05:18ZengAmerican Society for MicrobiologyMicrobiology Spectrum2165-04972025-01-0113110.1128/spectrum.01618-24Development of ptxD/Phi as a new dominant selection system for genetic manipulation in Cryptococcus neoformansMuthita Khongthongdam0Tanaporn Phetruen1Sittinan Chanarat2Laboratory of Molecular Cell Biology, Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok, ThailandLaboratory of Molecular Cell Biology, Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok, ThailandLaboratory of Molecular Cell Biology, Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok, ThailandABSTRACT Cryptococcus neoformans is a globally distributed pathogenic fungus posing a significant threat to immunocompromised individuals, particularly those with HIV/AIDS. Effective genetic manipulation tools are essential for understanding its biology and developing new therapies. However, current genetic tools, including the variation of versatile selectable markers, are limited. This study develops and validates the phosphite dehydrogenase gene (ptxD)/phosphite (Phi) selection system as a non-antibiotic selectable marker for genetic manipulation in C. neoformans. A codon-optimized ptxD gene from Pseudomonas stutzeri was cloned under the TEF promoter. Using the transient CRISPR-Cas9 coupled with electroporation system, we integrated the ptxD gene into the C. neoformans genome and assessed the impact of ptxD integration on cell growth and virulence factors. The ptxD/Phi system effectively selected transformed cells on Phi-containing media. Growth assays showed that ptxD integration did not adversely affect cell growth or key virulence factors, including pleomorphism, capsule size, and melanin production. Additionally, we successfully disrupted the ADE2 gene using this system, confirming its applicability for gene deletion. Taken together, the ptxD/Phi system provides a robust and versatile tool for genetic manipulation in C. neoformans, facilitating further research into its biology and pathogenicity.IMPORTANCECryptococcus neoformans is a type of fungus that can cause serious illnesses in people who have weakened immune systems, like those with HIV/AIDS. To better study this fungus and find new treatments, scientists need tools to change its genes in precise ways. However, the current tools available for this are somewhat limited. This research introduces a new tool called the phosphite dehydrogenase gene/phosphite system, which does not rely on antibiotics to work. It uses a gene from a different bacterium that helps select and grow only the fungus cells that have successfully incorporated new genetic information. This is particularly useful because it does not interfere with the normal growth of the fungus or the features that make it harmful (like its ability to change shape or produce protective coatings). By making it easier and more effective to manipulate the genetics of C. neoformans, this tool opens up new possibilities for understanding how this fungus operates and for developing therapies to combat its infections. This is crucial for improving the treatment of infections in vulnerable populations.https://journals.asm.org/doi/10.1128/spectrum.01618-24Cryptococcus neoformansgenetic manipulationgene deletionselectable markerptxD genephosphite dehydrogenase
spellingShingle Muthita Khongthongdam
Tanaporn Phetruen
Sittinan Chanarat
Development of ptxD/Phi as a new dominant selection system for genetic manipulation in Cryptococcus neoformans
Microbiology Spectrum
Cryptococcus neoformans
genetic manipulation
gene deletion
selectable marker
ptxD gene
phosphite dehydrogenase
title Development of ptxD/Phi as a new dominant selection system for genetic manipulation in Cryptococcus neoformans
title_full Development of ptxD/Phi as a new dominant selection system for genetic manipulation in Cryptococcus neoformans
title_fullStr Development of ptxD/Phi as a new dominant selection system for genetic manipulation in Cryptococcus neoformans
title_full_unstemmed Development of ptxD/Phi as a new dominant selection system for genetic manipulation in Cryptococcus neoformans
title_short Development of ptxD/Phi as a new dominant selection system for genetic manipulation in Cryptococcus neoformans
title_sort development of ptxd phi as a new dominant selection system for genetic manipulation in cryptococcus neoformans
topic Cryptococcus neoformans
genetic manipulation
gene deletion
selectable marker
ptxD gene
phosphite dehydrogenase
url https://journals.asm.org/doi/10.1128/spectrum.01618-24
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