Yor022c protein is a phospholipase A1 that localizes to the mitochondrial matrix

Phospholipid turnover and acyl chain remodeling in the yeast ER

The turnover of phospholipids plays an essential role in membrane lipid homeostasis by impacting both lipid head group and acyl chain composition. This review focusses on the degradation and acyl chain remodeling of the major phospholipid classes present in the ER membrane of the reference eukaryote Saccharomyces cerevisiae, i.e. phosphatidylcholine (PC), phosphatidylinositol (PI) and phosphatidylethanolamine (PE). Phospholipid turnover reactions are introduced, and the occurrence and important functions of phospholipid remodeling in higher eukaryotes are briefly summarized. After presenting an inventory of established mechanisms of phospholipid acyl chain exchange, current knowledge of phospholipid degradation and remodeling by phospholipases and acyltransferases localized to the yeast ER is summarized. PC is subject to the PC deacylation-reacylation remodeling pathway (PC-DRP) involving a phospholipase B, the recently identified glycerophosphocholine acyltransferase Gpc1p, and the broad specificity acyltransferase Ale1p. PI is post-synthetically enriched in C18:0 acyl chains by remodeling reactions involving Cst26p. PE may undergo turnover by the phospholipid: diacylglycerol acyltransferase Lro1p as first step in acyl chain remodeling. Clues as to the functions of phospholipid acyl chain remodeling are discussed.

Suppression of respiratory growth defect of mutant deficient in mitochondrial phospholipase A1 by overexpression of genes involved in coenzyme Q synthesis in Saccharomyces cerevisiae

DDL1 encodes a mitochondrial phospholipase A1 involved in acyl chain remodeling of mitochondrial phospholipids and degradation of cardiolipin in Saccharomyces cerevisiae. The deletion of DDL1 leads to respiratory growth defects. To elucidate the physiological role of DDL1, we screened for genes that, when overexpressed, suppress the respiratory growth defect of the DDL1 deletion mutant. Introduction of COQ8, COQ9, or COQ5, which are involved in coenzyme Q (CoQ) synthesis, using a multicopy vector suppressed the respiratory growth defect of the DDL1 deletion mutant. In contrast, introduction of COQ8 using a multicopy vector did not accelerate the growth of the deletion mutants of TAZ1 or CLD1, which encode an acyltransferase or phospholipase A2, respectively, involved in the remodeling of cardiolipin. These results suggest genetic interactions between the mitochondrial phospholipase A1 gene and the genes involved in CoQ synthesis.