The nagA gene of Penicillium chrysogenum encoding β‐ N ‐acetylglucosaminidase

We purified the β‐ N ‐acetylglucosaminidase from the filamentous fungus Penicillium chrysogenum and its N‐terminal sequence was determined, showing the presence of a mixture of two proteins (P1 and P2). A genomic DNA fragment was cloned by using degenerated oligonucleotides from the Nt sequences. The nucleotide sequence showed the presence of an ORF ( nagA gene) lacking introns, with a length of 1791 bp, and coding for a protein of 66.5 kDa showing similarity to acetylglucosaminidases. The NagA deduced protein includes P1 and P2 as incomplete forms of the mature protein, and contains putative features for protein maturation: an 18‐amino acid signal peptide, a KEX2 processing site, and four glycosylation motifs. The sequence just after the signal peptide corresponds to P2 and that after the KEX2 site to P1. The nagA transcript has a size of about 2.1 kb and is present until the end of the fermentation process for penicillin production. NagA is one of the most largely represented proteins in P. chrysogenum , increasing along the fermentation process. The suitability of the nagA promoter (P nagA ) for gene expression in fungi was demonstrated by expressing the bleomycin resistance gene ( ble R ) from Streptoalloteichus hindustanus in P. chrysogenum .