Distinctive structural features are shared by human, lapine, and murine acyloxyacyl hydrolases

Human acyloxyacyl hydrolase is an unusual lipase, found in phagocytic cells, that removes acyl chains from bacterial lipopolysaccharides (LPS) and glycerolipids. It is a heterodimer in which two glycosylated peptides are linked by disulfide bonding. The large subunit contains the active site serine, while the smaller subunit has striking sequence similarity to the saposins, peptide cofactors for several sphingolipid hydrolases. Since rabbits and mice are widely used for studies of LPS-animal interactions, we asked if murine and lapine AOAHs resemble the human enzyme. We report here that murine and lapine AOAHs share the distinctive features of the human AOAH primary sequence and have similar affinity for LPS. The structure of this unusual lipase appears to have been highly conserved.