Xiaoying Bian

State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Qingdao,

Identification of novel natural products and improvement of structural properties are the main missions of natural product research. Bacterial genome-sequencing projects reveal that the majority of natural product biosynthetic pathways are cryptic and thus offer the opportunity for the discovery of novel bioactives. Red/ET recombineering is a genetic and molecular biology technique based on defined homologous recombination systems for cloning and manipulate large size of DNA fragments, its development promotes the discovery and optimization of microbial natural products in the post-genomic era.

Firstly, the novel linear plus linear homologous recombination (LLHR) mediated cloning technique enables to directly clone large natural product biosynthetic genes (10-52 kb) from genomic DNA into an E. coli vector without genomic library. Followed by robust heterologous expression provides a feasible method for genome mining to discover new natural products and for activation of silent gene clusters. Secondly, the ccdB counterselectable marker coupled with recombineering was successfully applied to the site-directed mutagenesis of large natural product biosynthetic pathways, which can easily verify the function of biosynthetic genes and optimize the yield or structure of target compound. In this report, we will clarify this heterologous expression strategy by the successful reconstitution and production of several biosynthetic pathways (luminmide, luminmycin, lyngbyatoxin, colibactin and archazolid) in alternative hosts, thus construct a heterologous expression system for various microbial natural products and set the stage for subsequent combinatorial biosynthesis.

In summary, advanced recombineering mediated cloning and engineering of natural product biosynthetic pathways promotes the discovery and improvement of microbial natural products.