Functional expression of plant alternative oxidase decreases antimycin A-induced reactive oxygen species production in human cells.

Alternative oxidase (AOX) plays a pivotal role in cyanide-resistance respiration in the mitochondria of plants, fungi and some protists. Here we show that AOX from thermogenic skunk cabbage successfully conferred cyanide resistance to human cells. In galactose medium, HeLa cells with mitochondria-targeted AOX proteins were found to have significantly less reactive oxygen species production in response to antimycin-A exposure, a specific inhibitor of respiratory complex III. These results suggest that skunk cabbage AOX can be used to create an alternative respiration pathway, which might be important for therapy against various mitochondrial diseases.