title: Heat shock response of thermophilic fungi: membrane lipids and soluble carbohydrates under elevated temperatures.
abstract: The heat shock (HS) response is an adaptation of organisms to elevated temperature. It includes substantial changes in the composition of cellular membranes, proteins and soluble carbohydrates. To protect the cellular macromolecules, thermophilic organisms have evolved mechanisms of persistent thermotolerance. Many of those mechanisms are common for thermotolerance and the HS response. However, it remains unknown whether thermophilic species respond to HS by further elevating concentrations of protective components. We investigated the composition of the soluble cytosol carbohydrates and membrane lipids of the thermophilic fungi Rhizomucor tauricus and Myceliophthora thermophilaat optimum temperature conditions (41-43 °С), and under HS (51-53 °С). At optimum temperatures, the membrane lipid composition was characterized by a high proportion of phosphatidic acids (PA) (20-35 % of the total), which were the main components of the membrane lipids, together with phosphatidylcholines (PC), phosphatidylethanolamines (PE) and sterols (St). In response to HS, the proportion of PA and St increased, and the amount of PC and PE decreased. No decrease in the degree of fatty acid desaturation in the major phospholipids under HS was detected. The mycelium of all fungi at optimum temperatures contained high levels of trehalose (8-10 %, w/w; 60-95 % of the total carbohydrates), which is a hallmark of thermophilia. In contrast to mesophilic fungi, heat exposure decreased the trehalose level and the fungi did not acquire thermotolerance to lethal HS, indicating that trehalose plays a key role in this process. This pattern of changes appears to be conserved in the studied filamentous thermophilic fungi.
authors.affiliation: Laboratory of Experimental Mycology, Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Building 2, Leninsky Avenue 33, Moscow 119071, Russian Federation.
authors.forename: Elena A
authors.initials: EA
authors.lastname: Ianutsevich
authors.affiliation: Laboratory of Experimental Mycology, Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Building 2, Leninsky Avenue 33, Moscow 119071, Russian Federation.
authors.forename: Olga A
authors.initials: OA
authors.lastname: Danilova
authors.affiliation: Moscow State University of Fine Chemical Technologies named after M. V. Lomonosov, Moscow, Russian Federation.
authors.forename: Natalia V
authors.initials: NV
authors.lastname: Groza
authors.affiliation: Komarov Botanical Institute, Russian Academy of Sciences, St Petersburg, Russian Federation.
authors.forename: Ekaterina R
authors.initials: ER
authors.lastname: Kotlova
authors.affiliation: Laboratory of Experimental Mycology, Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Building 2, Leninsky Avenue 33, Moscow 119071, Russian Federation.
authors.forename: Vera M
authors.initials: VM
authors.lastname: Tereshina
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D018869:Heat-Shock Response / Q000502:physiology*; D006358:Hot Temperature; D008565:Membrane Proteins / Q000378:metabolism*; D025282:Mycelium / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D020103:Rhizomucor / Q000254:growth & development* / Q000502:physiology; D020037:Sordariales / Q000254:growth & development* / Q000502:physiology; D013261:Sterols / Q000378:metabolism; D000071436:Thermotolerance / Q000502:physiology; D014199:Trehalose / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D013261:Sterols; D014199:Trehalose