Extremophilic yeasts : plasma-membrane fluidity as determinant of stress tolerance

Turk, Martina (author), Plemenitaš, Ana (author), Gunde-Cimerman, Nina (author)

We report the first identification and characterisation of the glycerol-3-phosphate dehydrogenase (GPD) genes from extremely halophilic fungi. The black ascomycetous yeast Hortaea werneckii and the non-melanised basidiomycetous fungus Wallemia ichthyophaga inhabit similar hypersaline environments, yet they have two different strategies of haloadaptation throughGpd1-regulated glycerol synthesis. The extremely halotolerant H. werneckii codes for two salt-inducible GPD1 genes that show similar gene transcription regulation and have 98% amino-acid sequence identity between paraloguesč however, they have distinct effects when expressed heterologouslyin Saccharomyces cerevisiae gpd mutants. Only the HwGpd1B isoform complements the function of Gpd in the gpd1 mutant, whereas none of the Gpd1 isoforms can rescue the salt sensitivity of the gpd1gpd2 double mutant. The obligate halophile W. ichthyophaga codes for only one GPD1 orthologue, the transcription of which is less affected by salt when compared to the H. werneckii homologues. Heterologous expression of WiGPD1 in S. cerevisiae recovers halotolerance of the gpd1 and gpd1gpd2 mutant strains, which is probably due to the overall high amino-acid similarity of the Gpd1 protein in W. ichthyophaga and S. cerevisiae. Phylogenetic analysis of amino-acid sequences reveals that the evolutionary origins of all of these three novel enzymes correspond to the phylogeny of the fungal species from which the genes were identified.

• Language: English
• Keywords: EPR spectroscopy, halophilic/halotolerant yeast, plasma-membrane fluidity, psychrotolerant yeast, temperature
• Work type: Not categorized
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Year: 2011
• Number of pages: Str. 950-958
• Numbering: Vol. 115, no. 10
• PID: 20.500.12556/RUL-37522
• UDC: 579
• ISSN on article: 1878-6146
• DOI: 10.1016/j.funbio.2011.04.006
• COBISS.SI-ID: 2442319
• Publication date in RUL: 10.07.2015

Record is a part of a journal

• Title: Fungal biology
• Publisher: Elsevier
• ISSN: 1878-6146
• COBISS.SI-ID: 2396239