UC San Diego

Cyanobacteria are prolific producers of natural products with diverse structures and biological activities. Natural products are important for drug discovery and some of those isolated from cyanobacteria were found to have activities against cancer cells and infectious disease, or to relieve minor pain as anti-inflammatory drugs. However, slow growth rates, resistance to genetic engineering, and low yields limit the thorough investigation of many of these secondary metabolites within their native organisms. In this study, we describe and demonstrate the successful heterologous production of two bioactive secondary metabolites from marine cyanobacteria, cryptomaldamide and columbamide, in Anabaena sp. PCC 7120. This work resulted in the development and validation of new genetic tools and methods for the heterologous expression of large biosynthetic gene clusters. These tools include cloning vectors for transformation associated recombination in yeast and a new engineered strain of Anabaena along with a CRISPR/cpf1-based system that enables genetic engineering of large biosynthetic gene clusters in both Synechococcus elongatus PCC 7942 or Anabaena. This study showed that Anabaena is a more suitable host than S. elongatus for the production of marine cyanobacterial natural products. The heterologous expression of these biosynthetic gene clusters from marine cyanobacteria represents a significant opportunity to produce valuable compounds at a larger scale and for the further study of the mechanisms involved in the synthesis of these compounds.