Functional and Expression Analyses of the <italic toggle="yes">Pneumocystis MAT</italic> Genes Suggest Obligate Sexuality through Primary Homothallism within Host Lungs

ABSTRACT Fungi of the genus Pneumocystis are obligate parasites that colonize mammals’ lungs and are host species specific. Pneumocystis jirovecii and Pneumocystis carinii infect, respectively, humans and rats. They can turn into opportunistic pathogens in immunosuppressed hosts, causing severe pneu...

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Autores principales:	S. Richard, J. M. G. C. F. Almeida, O. H. Cissé, A. Luraschi, O. Nielsen, M. Pagni, P. M. Hauser
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2018
Materias:	complementation fission yeast RT-PCR gene expression heterologous gene expression Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/512dd763b65446fdb2fdb36c78bd2ba1
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spelling	oai:doaj.org-article:512dd763b65446fdb2fdb36c78bd2ba12021-11-15T15:53:26ZFunctional and Expression Analyses of the <italic toggle="yes">Pneumocystis MAT</italic> Genes Suggest Obligate Sexuality through Primary Homothallism within Host Lungs10.1128/mBio.02201-172150-7511https://doaj.org/article/512dd763b65446fdb2fdb36c78bd2ba12018-03-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02201-17https://doaj.org/toc/2150-7511ABSTRACT Fungi of the genus Pneumocystis are obligate parasites that colonize mammals’ lungs and are host species specific. Pneumocystis jirovecii and Pneumocystis carinii infect, respectively, humans and rats. They can turn into opportunistic pathogens in immunosuppressed hosts, causing severe pneumonia. Their cell cycle is poorly known, mainly because of the absence of an established method of culture in vitro. It is thought to include both asexual and sexual phases. Comparative genomic analysis suggested that their mode of sexual reproduction is primary homothallism involving a single mating type (MAT) locus encompassing plus and minus genes (matMc, matMi, and matPi; Almeida et al., mBio 6:e02250-14, 2015). Thus, each strain would be capable of sexual reproduction alone (self-fertility). However, this is a working hypothesis derived from computational analyses that is, in addition, based on the genome sequences of single isolates. Here, we tested this hypothesis in the wet laboratory. The function of the P. jirovecii and P. carinii matMc genes was ascertained by restoration of sporulation in the corresponding mutant of fission yeast. Using PCR, we found the same single MAT locus in all P. jirovecii isolates and showed that all three MAT genes are often concomitantly expressed during pneumonia. Extensive homology searches did not identify other types of MAT transcription factors in the genomes or cis-acting motifs flanking the MAT locus that could have been involved in MAT switching or silencing. Our observations suggest that Pneumocystis sexuality through primary homothallism is obligate within host lungs to complete the cell cycle, i.e., produce asci necessary for airborne transmission to new hosts. IMPORTANCE Fungi of the genus Pneumocystis colonize the lungs of mammals. In immunosuppressed human hosts, Pneumocystis jirovecii may cause severe pneumonia that can be fatal. This disease is one of the most frequent life-threatening invasive fungal infections in humans. The analysis of the genome sequences of these uncultivable pathogens suggested that their sexual reproduction involves a single partner (self-fertilization). Here, we report laboratory experiments that support this hypothesis. The function of the three genes responsible for sexual differentiation was ascertained by the restoration of sexual reproduction in the corresponding mutant of another fungus. As predicted by self-fertilization, all P. jirovecii isolates harbored the same three genes that were often concomitantly expressed within human lungs during infection. Our observations suggest that the sexuality of these pathogens relies on the self-fertility of each isolate and is obligate within host lungs to complete the cell cycle and allow dissemination of the fungus to new hosts.S. RichardJ. M. G. C. F. AlmeidaO. H. CisséA. LuraschiO. NielsenM. PagniP. M. HauserAmerican Society for Microbiologyarticlecomplementationfission yeastRT-PCRgene expressionheterologous gene expressionMicrobiologyQR1-502ENmBio, Vol 9, Iss 1 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	complementation fission yeast RT-PCR gene expression heterologous gene expression Microbiology QR1-502
spellingShingle	complementation fission yeast RT-PCR gene expression heterologous gene expression Microbiology QR1-502 S. Richard J. M. G. C. F. Almeida O. H. Cissé A. Luraschi O. Nielsen M. Pagni P. M. Hauser Functional and Expression Analyses of the <italic toggle="yes">Pneumocystis MAT</italic> Genes Suggest Obligate Sexuality through Primary Homothallism within Host Lungs
description	ABSTRACT Fungi of the genus Pneumocystis are obligate parasites that colonize mammals’ lungs and are host species specific. Pneumocystis jirovecii and Pneumocystis carinii infect, respectively, humans and rats. They can turn into opportunistic pathogens in immunosuppressed hosts, causing severe pneumonia. Their cell cycle is poorly known, mainly because of the absence of an established method of culture in vitro. It is thought to include both asexual and sexual phases. Comparative genomic analysis suggested that their mode of sexual reproduction is primary homothallism involving a single mating type (MAT) locus encompassing plus and minus genes (matMc, matMi, and matPi; Almeida et al., mBio 6:e02250-14, 2015). Thus, each strain would be capable of sexual reproduction alone (self-fertility). However, this is a working hypothesis derived from computational analyses that is, in addition, based on the genome sequences of single isolates. Here, we tested this hypothesis in the wet laboratory. The function of the P. jirovecii and P. carinii matMc genes was ascertained by restoration of sporulation in the corresponding mutant of fission yeast. Using PCR, we found the same single MAT locus in all P. jirovecii isolates and showed that all three MAT genes are often concomitantly expressed during pneumonia. Extensive homology searches did not identify other types of MAT transcription factors in the genomes or cis-acting motifs flanking the MAT locus that could have been involved in MAT switching or silencing. Our observations suggest that Pneumocystis sexuality through primary homothallism is obligate within host lungs to complete the cell cycle, i.e., produce asci necessary for airborne transmission to new hosts. IMPORTANCE Fungi of the genus Pneumocystis colonize the lungs of mammals. In immunosuppressed human hosts, Pneumocystis jirovecii may cause severe pneumonia that can be fatal. This disease is one of the most frequent life-threatening invasive fungal infections in humans. The analysis of the genome sequences of these uncultivable pathogens suggested that their sexual reproduction involves a single partner (self-fertilization). Here, we report laboratory experiments that support this hypothesis. The function of the three genes responsible for sexual differentiation was ascertained by the restoration of sexual reproduction in the corresponding mutant of another fungus. As predicted by self-fertilization, all P. jirovecii isolates harbored the same three genes that were often concomitantly expressed within human lungs during infection. Our observations suggest that the sexuality of these pathogens relies on the self-fertility of each isolate and is obligate within host lungs to complete the cell cycle and allow dissemination of the fungus to new hosts.
format	article
author	S. Richard J. M. G. C. F. Almeida O. H. Cissé A. Luraschi O. Nielsen M. Pagni P. M. Hauser
author_facet	S. Richard J. M. G. C. F. Almeida O. H. Cissé A. Luraschi O. Nielsen M. Pagni P. M. Hauser
author_sort	S. Richard
title	Functional and Expression Analyses of the <italic toggle="yes">Pneumocystis MAT</italic> Genes Suggest Obligate Sexuality through Primary Homothallism within Host Lungs
title_short	Functional and Expression Analyses of the <italic toggle="yes">Pneumocystis MAT</italic> Genes Suggest Obligate Sexuality through Primary Homothallism within Host Lungs
title_full	Functional and Expression Analyses of the <italic toggle="yes">Pneumocystis MAT</italic> Genes Suggest Obligate Sexuality through Primary Homothallism within Host Lungs
title_fullStr	Functional and Expression Analyses of the <italic toggle="yes">Pneumocystis MAT</italic> Genes Suggest Obligate Sexuality through Primary Homothallism within Host Lungs
title_full_unstemmed	Functional and Expression Analyses of the <italic toggle="yes">Pneumocystis MAT</italic> Genes Suggest Obligate Sexuality through Primary Homothallism within Host Lungs
title_sort	functional and expression analyses of the <italic toggle="yes">pneumocystis mat</italic> genes suggest obligate sexuality through primary homothallism within host lungs
publisher	American Society for Microbiology
publishDate	2018
url	https://doaj.org/article/512dd763b65446fdb2fdb36c78bd2ba1
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Functional and Expression Analyses of the <italic toggle="yes">Pneumocystis MAT</italic> Genes Suggest Obligate Sexuality through Primary Homothallism within Host Lungs

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