Staphylococcal lipases: molecular characterisation, secretion, and processing

Abstract

Up to date five different staphylococcal lipase genes, two of Staphylococcus aureus (sal-1 and sal-2), two of Staphylococcus epidermidis (sel-1 and sel-2) and one of Staphylococcus hyicus (sh1) have been cloned and sequenced. All corresponding proteins are organised as pre-pro-enzymes: the pre-region represents the signal peptide, the pro-region has a length between 207 and 267 amino acids, and the mature part comprises 380 to 400 amino acids. We found that the lipases are secreted in the pro-lipase form. The processing of the pro-form to the mature enzyme occurs extracellular by a specific protease. Interestingly the pro-lipase reveals not much less activity compared to the mature lipase. There are evidences that the pro-region acts as an intramolecular chaperone which facilitates translocation not only of the native lipase but also of a number of completely unrelated proteins fused to the pro-peptide. It was also observed that the pro-region protects the proteins from proteolytic degradation. While the Staphylococcus aureus and Staphylococcus epidermidis lipases have only lipase (esterase) activity, the related Staphylococcus hyicus enzyme (SHL) is distinguished by both lipase and phospho-lipase activity. The biochemical and catalytic properties of these lipases are described in the accompanying article (Simons, J.W., Götz, F., Egmont, M.R. and Verheij, H.M., 1998. Staphylococcal lipases: Biochemical properties. Accompanying article).