PolygalacturonaseII of Aspergillus niger was fragmented using CNBr and the NH2-terminal fragment and another fragment were partially sequenced. The polygalacturonaseII (pgaII) 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 NH2-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.
