CLONING, CHARACTERIZATION AND EXPRESSION OF PEPF, A GENE ENCODING A SERINE CARBOXYPEPTIDASE FROM ASPERGILLUS-NIGER

We have cloned a gene (pepF) encoding a serine carboxypeptidase, prote inase F (PEPF), from Aspergillus niger. The sequences were identified in a phage lambda genomic DNA library using a synthetic probe based on the N-terminal sequence of PEPF. Nucleotide sequence data from pepF g enomic and cDNA clones reveals that it is composed of four exons of 19 9, 283, 227 and 881 bp, interrupted by three introns of 53, 69 and 59 bp. The sequence of pepF codes for a polypeptide of 530 amino acids (a a), of which the first 52 aa are not present in the mature PEPF. This region may represent a pre-pro sequence that is removed by proteolytic cleavage at a monobasic cleavage site (Lys(52)). Northern blot analys is of total cellular RNA extracted from A. niger cells indicates that pepF is transcribed as a single 1.8-kb mRNA, which is regulated by nit rogen and carbon repression, specific induction and the pH of the cult ure medium.