Biotechnological production optimization of argyrins – a potent immunomodulatory natural product class

Argyrins represent a family of cyclic octapeptides exhibiting promising immunomodulatory activity via inhibiting mitochondrial protein synthesis, which leads to reduced IL‐17 production by the T‐helper 17 cells. Argyrins are formed by a non‐ribosomal peptide synthetase (NRPS), originating from the myxobacterial producer strains Archangium gephyra Ar8082 and Cystobacter sp. SBCb004. In this work, a previously established heterologous production platform was employed to provide evidence of direct D‐configured amino acid incorporation by the argyrin assembly line. An adenylation domain of the argyrin NRPS was characterized and shown to have a high preference for D‐configured amino acids. Eight novel argyrin derivatives were generated via biosynthetic engineering of the heterologous production system. The system was also optimized to enable formation of methylated argyrin C and D derivatives with improved immunosuppressive activity compared with their unmethylated counterparts. Furthermore, the optimization of cultivation conditions allowed exclusive production of one major derivative at a time, drastically improving the purification process. Importantly, engineering of transcription and translation initiation resulted in a substantially improved production titre reaching 350–400 mg l(−1). The optimized system presented herein thus provides a versatile platform for production of this promising class of immunosuppressants at a scale that should provide sufficient supply for upcoming pre‐clinical development.