Illuminating and exploiting programmed O-methylation in trans-AT polyketide synthases James Duncan, Prof. Józef Lewandowski and Prof. Gregory Challis University of Warwick, UK Natural products have been utilised as medicines (antibiotics and anticancer agents) and pesticides (herbicides, insecticides and fungicides) for many years. However increasingly there is a need for the development of more efficacious novel derivatives of these natural products to overcome some of their limitations. Many natural products are constructed by large multi-modular enzyme assembly lines that builds the molecule in stages. This provides an opportunity for rational bioengineering to create novel natural product derivatives. Unfortunately, a clear understanding of the structure, mechanism of action and substrate tolerance of these multi-modular protein ensembles is lacking. Therefore, there is a need to develop novel approaches to elucidate the mechanism and substrate specificity determinants of specific components of such machinery. O -methylation, a frequent modification of a class of natural product scaffolds called polyketides, plays an important role in the modulation of pharmacokinetic and pharmacodynamic properties. Trans -acyl transferase (AT) polyketide synthases (PKSs) employ specific submodules that catalyse O -methylation of beta -hydroxy thioester intermediates during chain assembly. To better understand the molecular function of an O -methylating submodule in the trans-AT PKS responsible for the biosynthesis of the antibiotic gladiolin, we aim to synthesise substrate analogues and site- specific covalent crosslinkers to trap O -methylating submodules in defined conformational states, facilitating structural elucidation. Additionally, we are exploring the substrate specificity of the O -methylating submodules in several trans-AT PKS (gladiolin, misakinolide and rhizopodin) by the synthesis of a range of beta -hydroxy pantetheine thioesters. This research will underpin future efforts to reprogram O -methylation in trans-AT PKSs, resulting in the creation of novel polyketide derivatives with altered methylation patterns.
P17
© The Author(s), 2022
Made with FlippingBook Learn more on our blog