Publications

• Roles of SAM and DDHD domains in mammalian intracellular phospholipase A1 KIAA0725p.

  Inoue H., Baba T., Sato S., Ohtsuki R., Takemori A., Watanabe T., Tagaya M., Tani K.

  Members of the intracellular phospholipase A1 family of proteins have been implicated in organelle biogenesis and membrane trafficking. The mammalian family comprises three members: phosphatidic acid-preferring phospholipase A1 (PA-PIA1)/DDHD1, p125/Sec23ip and KIAA0725p/DDHD2, all of which have a ... >> More

  Members of the intracellular phospholipase A1 family of proteins have been implicated in organelle biogenesis and membrane trafficking. The mammalian family comprises three members: phosphatidic acid-preferring phospholipase A1 (PA-PIA1)/DDHD1, p125/Sec23ip and KIAA0725p/DDHD2, all of which have a DDHD domain. PA-PLAI is mostly cytosolic, while KIAA0725p and p125 are more stably associated with the Golgi/endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC) and ER exit sites, respectively. Here we show that KIAAO725p and p125 are novel phosphoinositide-binding proteins. Deletion and mutational analyses of KIAAO725p suggested that a sterile alpha-motif (SAM), which is also present inp125, but not in cytosolic PA-PLAI, and the following DDHD domain comprise a minimal region for phosphatidylinositol 4-phosphate (Pl(4)P)-binding. A construct with mutations in the positively charged cluster of the SAM domain is defective in both phosphoinositide-binding and Golgi/ERGIC targeting. Consistent with the view that the Pl(4)P-binding is important for the membrane association of KIAA0725p, expression of phosphoinositide phosphatase Sacd reduces the association of expressed KIAAO725p with membranes. In addition, we show that deletion of the DDHD domain or introduction of point mutations at the conserved aspartate or histidine residues in the domain abolishes the phospholipase activity of KIAAO725p and PA-PLA1. Together, our results suggest that KIAAO725p is targeted to specific organelle membranes in a phosphoinositide-dependent manner, and that its SAM and DDHD domains are essential for its phosphoinositide-binding and phospholipase activity. << Less

  Biochim. Biophys. Acta 1823:930-939(2012) [PubMed] [EuropePMC]

• Membrane lipids have multiple effects on interfacial catalysis by a phosphatidic acid-preferring phospholipase A1 from bovine testis.

  Lin Q., Higgs H.N., Glomset J.A.

  We previously purified a cytosolic phospholipase A1 that could catalyze the preferential hydrolysis of phosphatidic acid in mixed-micelle assays. Here we studied the enzyme's interactions with unilamellar lipid membranes and examined effects of the lipids on enzyme binding, stability, and catalysi ... >> More

  We previously purified a cytosolic phospholipase A1 that could catalyze the preferential hydrolysis of phosphatidic acid in mixed-micelle assays. Here we studied the enzyme's interactions with unilamellar lipid membranes and examined effects of the lipids on enzyme binding, stability, and catalysis. A major finding was that membrane lipids could influence the stability, activity, and specificity of the enzyme under conditions where enzyme binding to the membranes was likely to be saturated. Thus, the enzyme was unstable at 37 degrees C in the absence of membranes but bound to membranes that contained anionic phosphoglycerides and could be stabilized by these membranes in the presence of albumin. The overall activity of the bound enzyme toward membrane phosphoglycerides, assayed in the presence of albumin, increased when phosphatidylethanolamine was substituted for phosphatidylcholine. Furthermore, the enzyme's catalytic preference for phosphatidic acid increased when cholesterol and diacylglycerol were included in the membranes, sn-1-stearoyl-2-arachidonoylphosphatidylethanolamine was substituted for sn-1-palmitoyl-2-oleoylphosphatidylethanolamine, and the concentration of phosphatidic acid was increased from 0 to 10 mol % of the total membrane phosphoglycerides. Finally, changes in the relative contents of phosphatidylcholine and phosphatidylserine in the membranes influenced the enzyme's catalytic preference for different molecular species of phosphatidic acid. These results provide the first available information about the enzyme's ability to interact with membranes and identify conditions that yield high enzyme activity toward membrane-associated phosphatidic acid. << Less

  Biochemistry 39:9335-9344(2000) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.