Molecular cloning, nucleotide sequence and expression of the gene encoding prepro‐polygalacturonasell of Aspergillus niger

PolygalacturonaseII of Aspergillus niger was fragmented using CNBr and the NH 2 ‐terminal fragment and another fragment were partially sequenced. The polygalacturonaseII ( pga II) gene was then isolated by using an oligonucleotide mixture based on the internal amino acid sequence as a probe. The nucleotide sequence of the pga II structural gene was determined. It was found that polygalacturonaseII is synthesized as a precursor having an NH 2 ‐terminal prepro‐sequence of 27 amino acids. The cloned gene was used to construct polygalacturonaseII over‐producing A. niger strains. PolygalacturonaseII was isolated from one such strain and was determined to be correctly processed and to be fully active.