Development of efficient genetic toolkits and heterologous chassis for bioprospecting of myxobacteria

Myxobacteria are renowned producers of structurally diverse bioactive natural products. Motivated by a comprehensive inventory of myxobacterial biosynthetic gene clusters (BGCs), we develop efficient genetic toolkits and construct a robust heterologous expression chassis. We identify a pair of Myxococcus-derived recombinases, designated MxRecET, that enables efficient genome editing in the model strain Myxococcus xanthus DK1622. The synergistic combination of MxRecET recombineering with the transposon-associated nuclease TnpB (ISDra2) enables versatile genetic manipulations, including seamless deletion of large DNA fragments (up to 200 kb), tandem editing of dual loci, and flexible single-nucleotide substitutions within a streamlined two-week workflow. This integrated technology, termed MxDIRECT, facilitates the rational engineering of DK1622 into a plug-and-play chassis designated MxPKS, featuring enhanced growth properties, elimination of competing pathways, an improved precursor supply, and increased robustness. The effectiveness of MxPKS is demonstrated through heterologous expression of four polyketide synthase BGCs, leading to the discovery of multiple unknown polyketides. This work establishes a foundation for accelerated bioprospecting of myxobacteria.