Structure and function of lysosomal phospholipase A2 and lecithin:cholesterol acyltransferase

Abstract

Lysosomal phospholipase A2 (LPLA2) and lecithin:cholesterol acyltransferase (LCAT) belong to a structurally uncharacterized family of key lipid metabolizing enzymes responsible for lung surfactant catabolism and for reverse cholesterol transport, respectively. Whereas LPLA2 is predicted to underlie the development of drug-induced phospholipidosis, somatic mutations in LCAT cause fish eye disease and familial LCAT deficiency. Here we describe several high resolution crystal structures of human LPLA2 and a low resolution structure of LCAT that confirms its close structural relationship to LPLA2. Insertions in the α/β hydrolase core of LPLA2 form domains that are responsible for membrane interaction and binding the acyl chains and head groups of phospholipid substrates. The LCAT structure suggests the molecular basis underlying human disease for most of the known LCAT missense mutations, and paves the way for rational development of new therapeutics to treat LCAT deficiency, atherosclerosis and acute coronary syndrome.

Properties and Biotechnological Applications of Acyl‐CoA:diacylglycerol Acyltransferase and Phospholipid:diacylglycerol Acyltransferase from Terrestrial Plants and Microalgae

“…Other conserved features include a salt bridge between an aspartate residue and an arginine residue and a lid region with a tryptophan residue, which is proposed to bind released fatty acid for efficient acylation. PDAT exhibits homology to human LCAT (26% identity) and phospholipase A 2 (27% identity), the structure of which was recently elucidated (Glukhova et al, 2015;Piper et al, 2015). Using the phospholipase A 2 structure, the AtPDAT1 model was determined using PHYRE software with a high confidence level ( Fig.…”

How the Same Core Catalytic Machinery Catalyzes 17 Different Reactions: the Serine-Histidine-Aspartate Catalytic Triad of α/β-Hydrolase Fold Enzymes

“…Phosphonates mimic the first tetrahedral intermediate, while sulfonates mimic the second tetrahedral intermediate, Chart 1. Structures of phosphonates bound to the active site have been solved for many lipases; for example, Burkholderia cepacia lipase (pdb id: 1hqd, 36 1ys1 37 ), two Candida lipases (pdb id: 1lbs, 38 1lpm 39 ), and human lysosomal phospholipase A2 (pdb id: 4×95 40 ) A structure of sulfonate bound to an esterase (pdb id: 3ia2 41 ) has also been solved. These structures, combined with detailed kinetic studies, firmly established the canonical esterase mechanism.…”

Preferential hydrolysis of truncated oxidized glycerophospholipids by lysosomal phospholipase A2

“…8). A formyl group, as found in both POVPC and PONPC, is known to react with unprotonated substrate at the active site (31,32). Possibly, the palmitoyl group at the sn-1 position of the truncated ox-PC tested is more hydrophobic and more easily accessible to the catalytic site than the truncated acyl group at the sn-2 position, thus explaining its preference as a scissile fatty acyl group.…”

“…Thus, the carbon chain length and polar group of the truncated aliphatic chain at the sn-2 position of the ox-PCs may play a substantial role in determining the preferential release of a long-chain acyl group at the sn-1 position of truncated ox-PCs by LPLA2. In addition, there is a helical wheel alignment between amino acid residues 138 and 155 of mouse LPLA2 that is located in proximity to the catalytic serine residue 165 (31,32). This is an amphipathic helix, and may be involved in the binding of PL and anti-human LPLA2 polyclonal antibody, respectively (Fig.…”