velikost textu

Plasma-membrane alkali-metal-cation transporters involved in salt tolerance of pathogenic Candida species

Upozornění: Informace získané z popisných dat či souborů uložených v Repozitáři závěrečných prací nemohou být použity k výdělečným účelům nebo vydávány za studijní, vědeckou nebo jinou tvůrčí činnost jiné osoby než autora.
Název:
Plasma-membrane alkali-metal-cation transporters involved in salt tolerance of pathogenic Candida species
Název v češtině:
Úloha transportéru kationtů alkalických kovů plasmatické membrány pathogenních druhů kvasinek v toleranci vůči solím
Typ:
Disertační práce
Autor:
Yannick Krauke, M.Sc., Ph.D.
Školitel:
RNDr. Hana Sychrová, DrSc.
Oponenti:
RNDr. Ivana Malcová, CSc.
Olga Hrušková Heidingsfeldová, Ph.D.
Id práce:
83461
Fakulta:
Přírodovědecká fakulta (PřF)
Pracoviště:
Katedra genetiky a mikrobiologie (31-140)
Program studia:
Molekulární a buněčná biologie, genetika a virologie (P1519)
Obor studia:
-
Přidělovaný titul:
Ph.D.
Datum obhajoby:
12. 7. 2010
Výsledek obhajoby:
Prospěl/a
Informace o neveřejnosti:
Práce byla vyloučena ze zveřejnění.
Jazyk práce:
Angličtina
Abstrakt:
summary of Ph.D. Thesis Conclusions All the aims of the thesis were achieved. The tolerance to alkali metal cations of four pathogenic Candida species was studied in detail and revealed differences among the yeasts. These differences in sall tolerance remained the same under various growth conditions. For the first time, the internal sodium and potassium concentrations of several Candida species were estimated under high salt-stress grolvth. The internal K./Na* ratio was not in relation with the salt tolerance revealing different adaptation mechanisms to salt stress in Candida species. A first study on combinatory use of fluconazole and NaCl revealed severe synergistic effects of both compounds, leading to grovvth inhibition and increased internal Na* concentrationsi n C. albicans.T he molecularb asis of this synergismr emains to be established. Ihe C. dubliniensis, C. glabrata and C. parapsilosis Cnhl NalH- antiporters were cloned and functionally characterized upon heterologous expression in S. cerevlslae to understand the mechanisms involved in the different salttolerances of Candida species. The three antiporters differed in their activity for alkali metal cations, which roughly correlated with the observed differences in salt tolerance among the species. Additionally, during the characterization of heteroiogously expressed antiporters, two antiporter chimeras were functionallyc haracterizeda nd comparedt o native proteins. The study of C. glabrata cnhlA mutant clearly proved that Cgcnhlp is involved in potassium tolerance and that it is the main potassium export system but that it has a minor functioni n sodium detoxificationin C. gtabrata.ln addition,t he C. glabrataE nal Na*-ATPase was characterized as a potential sodium export system in C. glabrata. Functional heterologous expression of CgEnalp showed its broad substrate specificity for alkali metal cations in S. cerevrslae. Deletion of CgENAI in C. glabrata proved its involvement in sodium detoxificationa nd revealedt he existenceo f another unknowns odium exports ystem. Finally, the expression of CgCNHI and CqENAI was compared and revealed that CgCNHI is constitutivelye xpressedi n contrastt o CqENAI whose expressioni s highlyi nduced upon salt and osmotic stresses. The detailed analysis ol C. glabrata Cnhlp and Enalp revealed distinct roles of the two proteins, Cnhlp being involved in K. homeostasis and Enalp in Na* detoxification. These findings are similar to results of homolog proteins in C. albicans and in sharp contrast to the situation in S. cerevlslae where the two transporters fulfil the same roles both in detoxificationa nd K* homeostasis.F urthers tudieso n Candida Ena Na*-ATPasesa nd Cnhl Na*/H* antjporters could clarify the mechanisms involved in the here described differences in salt tolerance of the four pathogenic Candida species. 12
Abstract v angličtině:
s u m m a r y o f P h . D .T h e s i s Conclusions All the aims of the thesis were achieved.The toleranceto alkali metal cations of four pathogenic Candida species was studied in detail and revealed differences among the yeasts. These differences in sall tolerance remained the same under various growth conditions.For the first time, the internal sodium and potassium concentrationsof several Candida species were estimatedunder high salt-stressgrolvth.The internalK./Na* ratio was not in relationwith the salt tolerance revealingdifferentadaptationmechanismsto salt stress in Candida species. A first study on combinatory use of fluconazole and NaCl revealed severe synergistic effects of both compounds, leading to grovvthinhibition and increased internal Na* concentrationsin C. albicans.The molecularbasis of this synergism remains to be established. Ihe C. dubliniensis, C. glabrata and C. parapsilosis Cnhl NalH- antiporters were cloned and functionally characterized upon heterologous expression in S. cerevlslae to understandthe mechanismsinvolved in the differentsalttolerancesof Candidaspecies. The three antiportersdifferedin their activityfor alkali metal cations,which roughlycorrelatedwith the observed differences in salt tolerance among the species. Additionally, during the characterizationof heteroiogously expressed antiporters, two antiporter chimeras were functionallycharacterizedand comparedto native proteins. The study of C. glabrata cnhlA mutant clearly proved that Cgcnhlp is involved in potassiumtolerance and that it is the main potassiumexport system but that it has a minor functionin sodium detoxification C. gtabrata.ln addition,the C. glabrata Enal Na*-ATPase in was characterized as a potential sodium export system in C. glabrata. Functional heterologousexpression of CgEnalp showed its broad substrate specificityfor alkali metal cations in S. cerevrslae.Deletionof CgENAI in C. glabrataproved its involvementin sodium and revealedthe existenceof another unknownsodium export system. Finally, detoxification the expression of CgCNHI and CqENAI was compared and revealed that CgCNHI is expressedin contrastto CqENAI whose expressionis highly induced upon salt constitutively and osmotic stresses. The detailed analysis ol C. glabrata Cnhlp and Enalp revealed distinct roles of the two proteins, Cnhlp being involved in K. homeostasis and Enalp in Na* detoxification. These findings are similarto results of homolog proteinsin C. albicansand in sharp contrast to the situation in S. cerevlslae where the two transportersfulfil the same roles both in detoxificationand K* homeostasis.Further studies on Candida Ena Na*-ATPasesand Cnhl Na*/H* antjporterscould clarifythe mechanismsinvolvedin the here describeddifferencesin salt toleranceof the four pathogenicCandidaspecies. 12
Dokumenty
Stáhnout Dokument Autor Typ Velikost
Stáhnout Text práce Yannick Krauke, M.Sc., Ph.D. 7.77 MB
Stáhnout Abstrakt v českém jazyce Yannick Krauke, M.Sc., Ph.D. 7 kB
Stáhnout Abstrakt anglicky Yannick Krauke, M.Sc., Ph.D. 706 kB
Stáhnout Posudek oponenta RNDr. Ivana Malcová, CSc. 70 kB
Stáhnout Posudek oponenta Olga Hrušková Heidingsfeldová, Ph.D. 1.44 MB
Stáhnout Záznam o průběhu obhajoby 541 kB