Deletion of the cardiolipin-specific phospholipase Cld1 rescues growth and lifespan defects in the tafazzin mutant: implications for Barth syndrome (605.4)

Cardiolipin (CL) that is synthesized de novo is deacylated to monolysocardiolipin (MLCL), which is reacylated by tafazzin. Remodeled CL contains mostly unsaturated fatty acids. In eukaryotes, loss of tafazzin leads to growth and respiration defects and, in humans, results in the life-threatening disorder Barth syndrome (BTHS). Tafazzin deficiency causes a decrease in the CL/MLCL ratio and decreased unsaturated CL species. Which of these biochemical outcomes contributes to the physiological defects is not known. Yeast cells have a single CL-specific phospholipase, Cld1, which can be exploited to distinguish between these outcomes. The cld1Δ mutant has decreased unsaturated CL, but the CL/MLCL ratio is similar to that of wild type cells. We show that cld1Δ rescues growth, life span, and respiratory defects of the taz1Δ mutant. This suggests that defective growth and respiration in tafazzin-deficient cells is caused by the decreased CL/MLCL ratio, not by a deficiency in unsaturated CL. CLD1 expression is inc...