Ypr140wp, 'the yeast tafazzin', displays a mitochondrial lysophosphatidylcholine (lyso-PC) acyltransferase activity related to triacylglycerol and mitochondrial lipid synthesis.

摘要

Identification of a protein capable of catalysing the acylation of lyso-PC (lyso-phosphatidylcholine (lysolecithin)) to form PC (lecithin) is reported; this is thought to be the 1st reported identification of this type of enzyme. The yeast protein, Ypr140w, was expressed in Escherichia coli cells and the resultant lyso-PC acyltransferase activity was associated with bacterial membranes. A Ypr140w-green fluorescent protein fusion was constructed, and studied in living yeast; fluorescence microscopy showed it to be targeted to the mitochondria. In contrast with wild-type cells, in the absence of acyl-CoA, a yeast mutant with the YPR140w gene deleted (Ypr140wDELTA) had no lyso-PC acyltransferase activity associated with the mitochondria. Ypr140wDELTA cells grown in the presence of lactate synthesized 2-fold more triacylglycerols compared with the wild-type. Moreover, their mitochondrial membranes contained less PC and cardiolipin, and the fatty acids composition of cardiolipin was greatly changed. These modifications were accompanied by a 2-fold increase in the respiration rates (states 3 and 4) of the mitochondria. The relationship between deletion of the YPR140w gene and the lipids composition of ypr140wDELTA cells is discussed.