The non-reducing disaccharide trehalose can serve as a protectant against a range of environmental stressors, such as heat, cold, or dehydration, in both prokaryotes and eukaryotes, with the exception of vertebrates. Here, we analyzed trehalose metabolism in the facultatively parasitic organism Acanthamoeba castellanii, known to respond to unfavorable external conditions by forming two resistant stages: a cyst, produced in the case of chronic stress, and a pseudocyst, formed in reaction to acute stress. The possible role of trehalose in the resistant stages was investigated using a combination of bioinformatic, molecular biological and biochemical approaches. Genes for enzymes from a widespread trehalose-6-synthase-trehalose-6-phosphate phosphatase (TPS-TPP) pathway and a prokaryotic trehalose synthase (TreS) pathway were identified. The expression patterns of the genes during encystation and pseudocyst formation were analyzed and correlated with the time course of cellular trehalose content determined mass spectrometrically. The data clearly demonstrate fundamental differences between encystation and pseudocyst formation at the level of cellular metabolism.

Biology Centre of the Czech Academy of Sciences and Faculty of Science University of South Bohemia 370 05 Ceske Budejovice Czech Republic

Centre of Excellence in Mass Spectrometry University of York Heslington York YO10 5DD UK; Department of Chemistry University of York Heslington York YO10 5DD UK

Centre of Excellence in Mass Spectrometry University of York Heslington York YO10 5DD UK; Technology Facility Department of Biology University of York Heslington York YO10 5DD UK

Institute of Immunology and Microbiology 1st Faculty of Medicine Charles University and General Faculty Hospital 128 00 Prague Czech Republic

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