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Proteome of tolerance fine-tuning in the human pathogen black yeast Exophiala dermatitidis

Tesei, Donatella, Marzban, Gorji, Marchetti-Deschmann, Martina, Tafer, Hakim, Arcalis, Elsa, Sterflinger, Katja
Journal of proteomics 2015 v.128 pp. 39-57
Exophiala dermatitidis, carbon, cold stress, dishwashers, drinking water, environmental factors, habitats, heat tolerance, hosts, humans, mass spectrometry, pathogenicity, pathogens, protein content, protein synthesis, proteins, proteome, stress response, temperature, yeasts
The black yeast Exophiala dermatitidis is a worldwide distributed agent of primary and secondary diseases in both immunocompromised and healthy humans, with a high prevalence in human-made environments. Since thermo-tolerance has a crucial role in the fungus persistence in man-dominated habitat and in its pathogenicity, three incubation temperatures (37, 45, 1°C) and two time spans (1h, 1week) were selected to simulate different environmental conditions and to investigate the effect of temperature on the proteome of E. dermatitidis CBS 525.76. Using a novel protocol for protein extraction from black yeasts, 2-D DIGE could be applied for characterization of changes in total protein spot abundance among the experimental conditions. A total of 32 variable proteins were identified by mass spectrometry. Data about protein functions, localization and pathways were also obtained. A typical stress response under non-optimal temperature could not be observed at the proteome level, whereas a reduction of the metabolic activity, mostly concerning processes as the general carbon metabolism, was detected after exposure to cold. These results suggest that a fine protein modulation takes place following temperature treatment and a repertoire of stable protein might be at the base of E. dermatitidis adaptation to altered growth conditions.E. dermatitidis is a pathogenic black yeast causing neurotropic infections, systemic and subcutaneous disease in a wide range of hosts, including humans. The discovery of the fungus high prevalence in man-made habitats, including sauna facilities, drinking water and dishwashers, generated concern and raised questions about the infection route. In the present work — which is the first contribution on E. dermatitidis proteome — the effect of different temperature conditions on the fungus protein pattern have been analyzed by using a gel-based approach and the temperature responsive proteins have been identified.The absence of a typical stress response following the exposure to non-optimal temperature was detected at the proteome level, along with a general reduction of the metabolic activity after exposure to cold. These results suggest that a very fine regulation of the protein expression as well as adaptations involving a basic set of stable proteins may be at the base of E. dermatitidis enormous ecological plasticity, which plays a role in the fungus distribution, also enabling the transition from natural to human habitat and to the human host.