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Although oxygen is essential for aerobic organisms, it also forms potentially harmful reactive oxygen species. For its simplicity, easy manipulation, and cultivation conditions, yeast is used as an attractive model in oxidative stress research. However, lack of polyunsaturated fatty acids (PUFAs) in yeast membranes makes yeast unsuitable for research in the field of lipid peroxidation. Therefore, we have constructed a yeast strain expressing a delta12 desaturase gene from the tropical rubber tree, Hevea brasiliensis. This yeast strain expresses the heterologous desaturase in an active form and, consequently, produces delta9/delta12 polyunsaturated fatty acids under inducing conditions. The functional expression of the heterologous desaturase did not affect cellular morphology or growth, indicating no general adverse effect on cellular physiology. However, the presence of PUFAs, changed the yeast’ s sensitivity to oxidative stress induced by hydrogen peroxide. This difference in sensitivity was followed by the formation of 4-hydroxy-2-nonenal (HNE), one of the end products of linoleic fatty acid peroxidation, which is known to play a role in cell growth control and signaling. HNE-protein adducts were also present at a significant, albeit lower, level under physiological conditions in the desaturase-expressing strain, in the absence of exogenous stressors. These data demonstrate that a yeast strain conditionally expressing delta12 desaturase provides a novel and attractive system to study physiological and pathophysiological processes induced by PUFA peroxidation, which are highly relevant to disease processes, such as cancer, in humans. |
