title: Adaptation to oxidative stress induced by polyunsaturated fatty acids in yeast.
abstract: To create a conditional system for molecular analysis of effects of polyunsaturated fatty acids (PUFA) on cellular physiology, we have constructed a strain of yeast (Saccharomyces cerevisiae) that functionally expresses, under defined conditions, the Delta12 desaturase gene from the tropical rubber tree, Hevea brasiliensis. This strain produces up to 15% PUFA, exclusively under inducing conditions resulting in production of 4-hydroxy-2-nonenal, one of the major end products of n-6 polyunsaturated fatty acid peroxidation. The PUFA-producing yeast was initially more sensitive to oxidative stress than the wild-type strain. However, over extended time of cultivation it became more resistant to hydrogen peroxide indicating adaptation to endogenous oxidative stress caused by the presence of PUFA. Indeed, PUFA-producing strain showed an increased concentration of endogenous ROS, while initially increased hydrogen peroxide sensitivity was followed by an increase in catalase activity and adaptation to oxidative stress. The deletion mutants constructed to be defective in the catalase activity lost the ability to adapt to oxidative stress. These data demonstrate that the cellular synthesis of PUFA induces endogenous oxidative stress which is overcome by cellular adaptation based on the catalase activity.
authors.affiliation: Rudjer Boskovic Institute, Zagreb, Croatia.
authors.forename: Ana
authors.initials: A
authors.lastname: Cipak
authors.forename: Morana
authors.initials: M
authors.lastname: Jaganjac
authors.forename: Oksana
authors.initials: O
authors.lastname: Tehlivets
authors.forename: Sepp D
authors.initials: SD
authors.lastname: Kohlwein
authors.forename: Neven
authors.initials: N
authors.lastname: Zarkovic
mesh_terms: D000222:Adaptation, Physiological; D002374:Catalase / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism / Q000502:physiology
chemical_list: D005231:Fatty Acids, Unsaturated; D002374:Catalase