Engineering and Analyzing Streptomyces strain for the Recombinant Protein Production

  Streptomyces strains are aerobic, gram-positive and mycelia-forming soil bacteria that produce useful compounds such as secondary metabolites and secreted hydrolytic enzymes. Streptomyces is an attractive host for various products, for example antibiotics, antifungals, and secreted native or recombinant proteins. Genetic tools for Streptomyces hosts have recently been developed in strain engineering. Previously, we have reported that some recombinant proteins were overexpressed in Streptomyces lividans host by using the engineering vector under the control of Streptoverticillium cinnamoneum Phospholipase D promoter.

  For the purpose to expand the cell factory system for the recombinant protein production, we investigated the following two things; 1) searching for useful enzymes from sequenced Streptomycesgenomes and 2) improving and mechanistic understanding of the protein production.

  To obtain novel useful enzymes, putative enzyme genes annotated from several Streptomyces genomes were expressed in the Streptomyceshost strain. We found some novel enzymes which showed unique activity and oligosaccharide production after the characterization of these expressed enzymes.

  To improve and understand the recombinant protein production, we examined the engineered and analytical approach of the host strain. We focused on the transcription factors for strain engineering. The mutation of the transcription factors is expected to change the expression levels of a wide range of the internal genes and to have an effect on the production yield. Several mutant strains were actually found to change the expression level of the recombinant protein compared to the wild-type strain. At the same time, we took the analytical approach to understand important factors during the protein production in some aspects, such as the metabolic aspect. Here, we summarized our research and findings in the presentation.