CLONING AND SEQUENCING OF PHOSPHOLIPASE-B GENE FROM THE YEAST TORULASPORA-DELBRUECKII

The extracellular phospholipase B gene from baker's yeast Torulaspora delbrueckii was cloned and sequenced. Analysis of DNA sequence data revealed an open reading frame (ORF) encoding a 649-amino acid protein, that included amino acid sequences obtained from the purified enzyme. Comparison of these sequence data with the N-terminal amino acid sequence of the enzyme indicated that this secreted protein is synthesized as a large precursor with a 21-amino acid N-terminal extension to the mature enzyme of 628 amino acids. A homology search was carried out between phospholipase B from T. delbrueckii and Penicillium notatum. The deduced amino acid sequence of the cloned phospholipase B was homologous (about 50% identity) to phospholipase B from P. notatum, and contained six conserved regions. The transcriptional level of the phospholipase B gene in different growth phases of the cells was investigated by Northern blot analysis. The level of mRNA of the phospholipase B gene was higher in the cells from early exponential and stationary phases.