Biochemical properties of staphylococcal (phospho)lipases.

Various staphylococci secrete lipases which require calcium ions for activity, and have profound preferences for substrates with different chain lengths. The lipase from Staphylococcus hyicus is exceptional since it has higher phospholipase than lipase activity. This paper gives an overview of the biochemical properties of these enzymes. It appears that chain length selectivity of these enzymes resides in the acylation step. Interfaces mainly influence the acylation step. Calcium ions do not influence the rate of acylation or deacylation although stabilise the enzyme against denaturation. Molecular modelling based on the X-ray structure of Pseudomonas glumae lipase was used to construct a model of the staphylococcal lipases. With this model the position of serveral residues involved in stubstrate selectivity was predicted. Moreover, a sequence element could be assigned that may function as the so-called lid domain in staphylococcal lipases. Sequence alignment of four staphylococcal lipases, and lipases from P. glumae and Bacillus thermocatenulatus identified several potential calcium ligands, one of which was verified by site directed mutagensesis. It is concluded that stabilisation of lipases by calcium ions might be a more general phenomenon than recognized so far.