Biomimetic synthesis, biosynthetic pathway engineering and structure activities studies of unique glycosolyated macrolactams – BiBiMAC

The chemical analysis of specialized microbial symbionts yields a deeper understanding of the evolution of symbiotic systems, and at the same time grants access to intrinsically bioactive natural products. It is only now that the impact of these natural products on the discovery of novel antibiotics with potential applications for human health is being realized. Yet, novel sources of antibiotics are needed since the use of antibiotics inevitably selects for resistant pathogens. In times of multiresistant strains such as methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant Enterococci (VRE), the demand for new classes of antibiotics and the discovery of new targets, is high.
Broadly, the project aims to elucidate the chemical repertoire of a bacterial symbiont, Amycolatopsis M39, of fungus-growing termites. Attractive features and goals of this approach include: (1) The targeted and genome-driven analysis of chemically poorly studied symbiotic bacteria and their respective secondary metabolites, which have undergone evolutionary selection for their activity and ecological role; (2) modern semi and total synthesis to evaluate the absolute structure of pharmacologically interesting target structures and biosynthetic intermediates. And (3) the generation of a substrate library of intrinsically bioactive secondary metabolites. We intend to capitalize on recent advances in organic method development, DNA sequencing and genome mining approaches, as well as synthetic biology. We aim to link natural products to their genomic basis to understand the underpinnings of their biosynthesis, and we will use the generated information to build up a more general discovery and evaluation platform. This project benefits from longstanding collaborations with other academic partners having strong expertise in chemical ecology and biosynthesis, and the presence of an in-house pharmacological and pre-clinical evaluation platform. Most importantly, the key element of this proposal is the synergistic interaction between the partners of the collaborative research consortium, which is necessary to tackle the outlined ambitious tasks.
The following three specific aims will be addressed during the course of the 3-year funding period: First, we will determine the absolute structure of the antifungal natural product macrotermycin A and derivatives by using an efficient and modular strategy, a strategy which provides at the same time thioester precursors for biosynthetic pathway studies. Furthermore, structurally simplified macrotermycins should be synthesized to enable structure-activity studies. Secondly, we aim to understand and subsequently manipulate the putative biosynthetic pathway of macrotermycins using a heterologous expression system, that can be transferred to the analysis of other not yet fully characterized gene clusters within the genome of M39 to fully harvest the chemical potential. Thirdly, we aim to elucidate the means by which other encoded biosynthetic gene clusters are induced and identify the respective secondary metabolites.