PURIFICATION, GLYCOSYLATION AND SECRETION OF A REPRESSIBLE ACID PHOSPHATASE OF Yarrowia lipolytica

Abstract

A repressible acid phosphatase of Yarrowia lipolytica was purified and antibodies directed againstits proteic portion wereobtained (1). Immunoprecipitation experiments have madeit clear that this enzyme is very heterogeneous. Suchexperiments have also led to the detection of a precursor of about 86 kDa in cells grown under conditions of derepression. This precursor corresponds to a partially glycosylated form of the enzyme. The heterogeneity shown bythe enzyme is due toits oligosaccharidic component since a single sharp band of 58-60 kDa appears when the immunoprecipitates of the cellular extracts are treated with endo H. When the extracts from derepressed cells treated with tunicamycin were immunoprecipitated with the antibodies, two polypeptides of 54 and 52 kDa appeared. Preliminary experimental evidence supports the idea that these must be the mature non-glycosylated enzymatic protein and its precursor containing the signal sequence. Under normal conditions of derepression, cells secrete a glycosylated polypeptide into the culture medium, whereasin the Presenceof tunicamycin two polypeptides of 38 and 20 kDa, whicharerelated immunologically to phosphatase, are detected in the culture medium.