Efficient production of aculeacin A acylase in recombinant Streptomyces strains

Abstract

The productivities of aculeacin A acylase in various recombinant Streptomyces strains were examined. When the acylase gene was introduced into six species (S. lividans, S. albus, S. ambofaciens, S. parvulus, S. griseus and S. avermitilis) using Streptomyces multi-copy vector pIJ702, all strains produced the acylase extracellularly. The recombinant S. Griseus was the most efficient producer of the enzyme, producing 25-fold more than the original producer, Actinoplanes utahensis. On the other hand, the recombinant strains of S. lividans and S. avermitilis showed almost the same productivity as A. utahensis. The purified recombinant acylases from four strains, S. albus, S. ambofaciens, S. parvulus and S. griseus, were composed of two subunits; however, the molecular mass values of their small subunits were higher than that of the original acylase. Further, immunoblot analysis showed that the presumed precursor peptide and its degradation products were also detected in the low-producing strains, A. utahensis and S. avermitilis. These findings indicate that the productivity of the acylase was affected by proteolytic activity in the host strains.