Investigating bottromycin biosynthesis by X-ray crystallography and in vitro engineering of the pathway

Since their discovery in the early 20th century antibiotics have been an essential cornerstone of modern medicine and contributed significantly to the increase in life expectancy over the past century. Unfortunately the wide availability of and easy access to antibiotics has led to an overuse in most developed countries, which combined with inappropriate antibiotic treatments on a global scale has led to a seemingly ever faster development of antibiotic resistance in bacteria. This, coupled with a severe reduction of antimicrobial research by pharmaceutical companies over the past 20 years, has led to antibiotic resistance becoming a major threat to public health. Almost all antibiotics approved for clinical use today are natural products isolated from microorganisms and higher plants, or chemical derivatives thereof, and the traditional approaches to overcome resistance in bacteria have been either total chemical synthesis of derivative molecules or chemical modification of the natural product itself. To combat resistance, especially multi-drug-resistance, new compounds that exploit novel bacterial targets and/or offer drastically different chemical scaffolds are required. With less than ~85 % of higher plants and less than ~1 % of microorganisms screened for bioactive compounds to date they still offer a vast reservoir of new natural products as potential lead compounds. This proposal seeks to understand key steps in the biosynthesis of the potent and novel natural product antibiotics bottromycins.

Bottromycins are cyclic peptides that target the A site of the prokaryotic 50S ribosome. They are synthesized from a ribosomally derived precursor peptide that is tailored by a series of enzymatic chemical transformations. We will express and purify all enzymes essential for bottromycin biosynthesis, reconstitute their activity in vitro and analyse their reaction mechanisms and substrate specificity through X-ray crystallography and a variety of biophysical and biochemical techniques. We will then use the newly gained insights to engineer the biosynthetic pathway in vitro to introduce chemical properties beyond the reach of the 20 natural amino acids this pathway is normally confined to. A key enzyme of the pathway, the macrocyclase, will be used to cyclize unrelated biological and chemical molecules to access the potential of ring structures as bioactive molecules.

Beteiligte Gruppen

Geldgeber / Förderer

DFG - Deutsche Forschungsgemeinschaft

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