Publications

• Positional specificity of lysosomal phospholipase A2.

  Abe A., Hiraoka M., Shayman J.A.

  Lysosomal phospholipase A(2) (Lpla2) is highly expressed in alveolar macrophages and may mediate the phospholipid metabolism of surfactant. Studies on the properties of this phospholipase are consistent with the presence of both phospholipase A(1) and phospholipase A(2) activities. These activitie ... >> More

  Lysosomal phospholipase A(2) (Lpla2) is highly expressed in alveolar macrophages and may mediate the phospholipid metabolism of surfactant. Studies on the properties of this phospholipase are consistent with the presence of both phospholipase A(1) and phospholipase A(2) activities. These activities were studied through the production of O-acyl compounds, produced by the transacylase activity of Lpla2. Liposomes containing POPC and N-acetylsphingosine (NAS) were incubated with the soluble fraction obtained from MDCK cells stably transfected with the mouse Lpla2 gene. Two 1-O-acyl-NASs, 1-O-palmitoyl-NAS and 1-O-oleoyl-NAS, were produced by Lpla2. The formation rate of 1-O-oleoyl-NAS was 2.5-fold that of 1-O-palmitoyl-NAS. When 1-oleoyl-2-palmitoyl-sn-glycero-3-phosphocholine (OPPC) was used, the formation rate of 1-O-oleoyl-NAS was 5-fold higher than that of 1-O-palmitoyl-NAS. Thus, Lpla2 can act on acyl groups at both sn-1 and sn-2 positions of POPC and OPPC. When 1-palmitoyl-2-unsaturated acyl-sn-glycero-3-phosphocholines were used as acyl donors, the transacylation of the acyl group from the sn-2 position to NAS was preferred to that of the palmitoyl group from the sn-1 position. An exception was observed for 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC), for which the formation rate of 1-O-palmitoyl-NAS from PAPC was 4-fold greater than that of 1-O-arachidonoyl-NAS. Thus, Lpla2 has broad positional specificity for the sn-1 and sn-2 acyl groups in phosphatidylcholine and phosphatidylethanolamine. << Less

  J. Lipid Res. 47:2268-2279(2006) [PubMed] [EuropePMC]

  This publication is cited by 38 other entries.

• Determinants of pH profile and acyl chain selectivity in lysosomal phospholipase A2.

  Hinkovska-Galcheva V., Kelly R., Manthei K.A., Bouley R., Yuan W., Schwendeman A., Tesmer J.J.G., Shayman J.A.

  Lysosomal phospholipase A2 (LPLA₂) is characterized by broad substrate recognition, peak activity at acidic pH, and the transacylation of lipophilic alcohols, especially <i>N</i>-acetyl-sphingosine. Prior structural analysis of LPLA₂ revealed the presence of an atypical acidi ... >> More

  Lysosomal phospholipase A2 (LPLA₂) is characterized by broad substrate recognition, peak activity at acidic pH, and the transacylation of lipophilic alcohols, especially <i>N</i>-acetyl-sphingosine. Prior structural analysis of LPLA₂ revealed the presence of an atypical acidic residue, Asp13, in the otherwise hydrophobic active site cleft. We hypothesized that Asp13 contributed to the pH profile and/or substrate preference of LPLA₂ for unsaturated acyl chains. To test this hypothesis, we substituted Asp13 for alanine, cysteine, or phenylalanine; then, we monitored the formation of 1-<i>O</i>-acyl-<i>N</i>-acetylsphingosine to measure the hydrolysis of <i>sn</i>-1 versus <i>sn</i>-2 acyl groups on a variety of glycerophospholipids. Substitutions with Asp13 yielded significant enzyme activity at neutral pH (7.4) and perturbed the selectivity for mono- and double-unsaturated acyl chains. However, this position played no apparent role in selecting for either the acyl acceptor or the head group of the glycerophospholipid. Our modeling indicates that Asp13 and its substitutions contribute to the pH activity profile of LPLA₂ and to acyl chain selectivity by forming part of a hydrophobic track occupied by the scissile acyl chain. << Less

  J. Lipid Res. 59:1205-1218(2018) [PubMed] [EuropePMC]

  This publication is cited by 22 other entries.