Synthetic biology of non-ribosomal peptide synthetases to generate new peptides
Natural products (NPs) generated by microbial non-ribosomal peptide synthetases (NRPS) represent several very important and valuable clinical antibiotics, immune-suppressive and anti-cancer drugs. NPs have gone on to inspire several synthetic peptides that are used clinically, but contain amino acids (AAs) or other building blocks that are not found in nature. However, with >500 identified AAs and additional peptide modifications like glycosylation or cyclization, the chemical diversity in NRPS-derived peptides is far larger than proteins and has not yet been fully explored. The modular nature of NRPS suggests the possibility to manipulate them, subsequently leading to the production of non-natural NPs. With an eXchange Unit (XU) concept, developed in Photorhabdus, Xenorhabdus and Bacillus, we have recently identified efficient ways for NRPS manipulation enabling the de novo assembly of novel NRPS for the production of new-to-nature NPs in excellent production yields of >250 mg/L. Within SYNPEP we will expand this approach to other bacterial genera producing peptide NPs. We will identify unusual NRPS systems, analyse them bioinformatically, validate the function of novel NRPS units experimentally and combine high-throughput molecular biology, microfluidics for bioactivity screening, rapid NP identification and structure elucidation to produce potentially any peptide or a peptide library of 2-15 amino acids in <4 weeks, in a semi-automated manner. In contrast to chemical peptide synthesis this production pipeline is more economical, sustainable and scalable. The NPs are produced by bacterial cells in aqueous media using cheap energy sources and the bacterial cultures can be easily scaled up when larger NP amounts are needed. We will also develop NRPS units that accept synthetic building blocks currently not found in natural NRPS. These ‘synthetic’ NRPS units will enable the simplified chemical derivatization of the produced NPs for further compound diversification.