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The role of polyamines in the pathobiology of the emergent fungal pathogen emergomyces africanus
Thesis (MSc)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2023
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| _version_ | 1867613920352534528 |
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| access_status_str | Open Access |
| author | Koroleva, Elizaveta |
| author2 | Botha, Alfred |
| author_browse | Botha, Alfred Koroleva, Elizaveta |
| author_facet | Botha, Alfred Koroleva, Elizaveta |
| author_sort | Koroleva, Elizaveta |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/128393 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:43:48.768Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/128393 The role of polyamines in the pathobiology of the emergent fungal pathogen emergomyces africanus Koroleva, Elizaveta Botha, Alfred Toplis, Barbra Stellenbosch University. Faculty of Science. Dept. of Microbiology. Polyamines -- Physiological effect Emergomyces africanus Fungal pathogens Polyamines -- Metabolism -- Inhibitors UCTD Thesis (MSc)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Emergomyces africanus is an emergent dimorphic pathogen that causes emergomycosis, a systemic fungal infection with severe morbidity and mortality, in immunocompromised patients. This fungus is the most prevalent causative agent of emergomycosis in South Africa. Although little is known about this organism, its thermally induced morphological transition from a mycelial to a pathogenic yeast-like phase in the human host is a notable virulence mechanism. The yeast-like phase allows for the proliferation and dissemination of the fungus inside the host. Research suggests that polyamines may play a pivotal role in dimorphism, but the functions of these biogenic amines in fungi remain enigmatic. The aim of this work was to investigate the polyamine metabolism of E. africanus and obtain an indication of the role of polyamines in the dimorphism of the fungus. Using ultraperformance liquid chromatography tandem mass spectrometry analysis, and enzyme activity assays of key polyamine synthesis enzymes, polyamine production by two clinical strains of E. africanus (JX398291 and JX398293) was evaluated in both their mycelial and yeast-like phases. Additionally, growth in the presence of exogenous polyamines was quantified and the effect of polyamine biosynthesis inhibitors cyclohexylamine (CHA) and difluoromethylornithine (DFMO) on the growth and dimorphic transition of the fungus was investigated. In this first report on the polyamine profile of E. africanus, spermidine was revealed as the major intracellular polyamine. A variety of secreted polyamines was detected, with spermidine and agmatine constituting the major proportion, with smaller proportions of putrescine and cadaverine. The activity of several key polyamine biosynthesis enzymes was detected in both phases, including arginine decarboxylase, agmatinase, arginase and ornithine decarboxylase. Significant differences in enzyme expression were observed between strains and morphological phases: arginase activity was higher in the mycelial phase (p ≤ 0.001), whereas ornithine decarboxylase (p ≤ 0.015) and agmatinase (p = 0.023) activities were higher in the yeast-like phase. Agmatinase upregulation aligned with enhanced growth in the presence of exogenous agmatine in the yeast-like phase. Of the two tested inhibitors, only CHA significantly (p ≤ 0.011) affected fungal growth, with similar responses in mycelial and yeast-like phases. Interestingly, JX398293 showed improved growth at lower CHA concentrations, whereas JX398291 growth was reduced. Both CHA and DFMO attenuated dimorphic switching, with strain-specific differences in inhibitor potency. Supplementation with putrescine or spermidine together with the inhibitors alleviated the inhibitory effect. Notably, the addition of spermidine improved the switch to a significantly (p ≤ 0.025) higher efficiency than under control conditions. Differences in switching efficiency were also observed between the two strains, suggesting intraspecies differences in virulence. Taken together, our study provides compelling evidence that polyamines play a role in the pathobiology and dimorphism of E. africanus. AFRIKAANSE OPSOMMING: Emergomyces africanus is 'n ontluikende dimorfiese patogeen wat emergomikose veroorsaak, 'n sistemiese fungusinfeksie wat ernstige morbiditeit en mortaliteit onder immuungekompromeerde pasiënte tot gevolg het. Hierdie fungus is die mees algemene oorsaak van emergomikose in Suid-Afrika. Alhoewel min oor hierdie organisme bekend is, is die termies-geïnduseerde morfologiese omskakeling van ’n miseliale na 'n patogeniese gisagtige fase binne die menslike gasheer 'n belangrike virulensie-meganisme. Die gisagtige fase veroorsaak die verspreiding en vermeerdering van die fungus binne die gasheer. Navorsing dui aan dat poliamiene 'n sentrale rol in dimorfisme kan speel, alhoewel die funksies van hierdie biogeneniese amiene in fungi duister bly. Die doel van hierdie studie was om die poliamienmetabolisme van E. africanus te ondersoek en 'n aanduiding te kry van die rol van poliamiene in die dimorfisme van hierdie fungus. Deur ultraprestasie vloeistofkromatografie tandem massaspektrometrie analise en ensiem-aktiwiteitstoetse van sleutel poliamiensintese ensieme te gebruik, was die poliamienproduksie van twee kliniese stamme van E. africanus (JX398291 en JX398293) in beide hul miseliale en gisagtige fases geëvalueer. Daarbenewens was die groei in die teenwoordigheid van eksogene poliamiene gekwantifiseer, en die effek van die poliamienbiosintese-inhibeerders sikloheksielamien (SHA) en difluorometielornitien (DFMO) op die groei en dimorfiese omskakeling van die fungus ondersoek. In hierdie eerste verslag oor E. africanus se poliamienprofiel, rapporteer ons dat spermidien die hoof-intrasellulêre poliamien is. 'n Verskeidenheid uitgeskeide poliamiene is waargeneem, waarvan spermidien en agmatien die grootste gedeelte uitgemaak het, met kleiner proporsies putresien en kadawerien. Die aktiwiteit van verskeie sleutel poliamienbiosintese ensieme is in beide fases opgespoor, insluitend arginien dekarboksilase, agmatinase, arginase en ornitien dekarboksilase. Betekenisvolle verskille in ensiemuitdrukking tussen stamme en morfologiese fases is waargeneem: arginase aktiwiteit was hoër in die miseliale fase (p ≤ 0.001), terwyl ornitien dekarboksilase (p ≤ 0.015) en agmatinase (p = 0.023) aktiwiteite hoër in die gisagtige fase was. Agmatinase-opregulering was in ooreenstemming met verhoogde groei in die teenwoordigheid van eksogene agmatien in die gisagtige fase. Van die twee getoetste inhibeerders het slegs SHA die fungusgroei betekenisvol beïnvloed (p ≤ 0.011), met soortgelyke reaksies in miseliale en gisagtige fases. Dit is interessant dat JX398293 verbeterde groei getoon het by laer SHA konsentrasies, terwyl die groei van JX398291 verminder is. Beide SHA en DFMO het dimorfiese omskakeling verswak, met stam-spesifieke verskille in inhibeerdersterktes. Die byvoeging van putresien of spermidien saam met die inhibeerders het inhiberende effek verlig. Die byvoeging van spermidien het die omskakeling tot 'n aansienlike (p ≤ 0.025) hoër doeltreffendheid as onder kontrole-kondisies verbeter. Verskille in omskakelingsdoeltreffendheid is ook tussen die twee stamme waargeneem, wat dui op intraspesie verskille in virulensie. Saamgevat, verskaf ons studie oortuigende bewyse dat poliamiene ‘n rol in die patobiologie en dimorfisme van E. africanus speel. Masters 2023-02-19T06:12:24Z 2023-08-30T13:05:47Z 2023-02-19 2023-02-19T06:12:24Z 2023-08-31T09:18:34Z 2023-02-19T06:12:24Z 2023-08-31T09:18:34Z 2023-03 Thesis https://scholar.sun.ac.za/handle/10019.1/128393 en Stellenbosch University application/pdf xvi, 105 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Polyamines -- Physiological effect Emergomyces africanus Fungal pathogens Polyamines -- Metabolism -- Inhibitors UCTD Koroleva, Elizaveta The role of polyamines in the pathobiology of the emergent fungal pathogen emergomyces africanus |
| title | The role of polyamines in the pathobiology of the emergent fungal pathogen emergomyces africanus |
| title_full | The role of polyamines in the pathobiology of the emergent fungal pathogen emergomyces africanus |
| title_fullStr | The role of polyamines in the pathobiology of the emergent fungal pathogen emergomyces africanus |
| title_full_unstemmed | The role of polyamines in the pathobiology of the emergent fungal pathogen emergomyces africanus |
| title_short | The role of polyamines in the pathobiology of the emergent fungal pathogen emergomyces africanus |
| title_sort | role of polyamines in the pathobiology of the emergent fungal pathogen emergomyces africanus |
| topic | Polyamines -- Physiological effect Emergomyces africanus Fungal pathogens Polyamines -- Metabolism -- Inhibitors UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/128393 |
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