Heterologous expression and engineering of Mycosporine-like amino-acid (MAA) biosynthetic gene clusters in Streptomyces hosts Sopida Wongwas 1,2 , Christophe Corre 1,2 1 School of Life Sciences, University of Warwick, UK, 2 Department of Chemistry, University of Warwick, UK Current commercial sunscreens have been found to be toxic to aquatic life; for example, causing coral bleaching 1 . Therefore, the use of natural products as sunscreens is a promising alternative to avoid environmental damages. Mycosporine-like amino acids (MAAs) are a group of natural product sunscreens that can absorb UV-A and/or UV-B radiation. They naturally act as photoprotective UV filters to several marine and terrestrial organisms. The aim of this project is to produce a range of known and novel MAAs using engineered plasmids and Streptomyces coelicolor M145 and M1152 hosts. Streptomyces bacteria are known as prolific producers of secondary metabolites and have been established as “superhosts” for the expression of biosynthetic gene clusters 2 . The biosynthesis of the MAA, Mycosporine-glycine, is directed by a cluster of three genes, mysABC , in Rhodococcus fascians D188 3 . In this project, the Streptomyces integrative plasmid containing mysABC genes under the control of a strong synthetic promoter was designed and conjugated into S. coelicolor M1152. LC-MS analyses revealed that the resulting strains produced mycosporines-glycine. The NRPS-like gene was used to produce the additional enzyme to add extra structures to the MAA backbone. The A-domain in NRPS-like enzymes is specific to particular structures. Hence, the additional group can be predicted. The Streptomyces strains with the NRPS-like gene from Moorea producens were supplemented with mycosporine-glycine and a new UV absorbing molecule which absorbed UV at 341 nm was produced. The next stages of the project will involve structure elucidation and determination of photochemical properties of the novel MAAs using NMR spectroscopy and ultrafast laser spectroscopy. References 1. Danovaro, R. et al. (2008) ‘Sunscreens cause coral bleaching by promoting viral infections’, Environmental Health Perspectives . doi: 10.1289/ehp.10966. 2. Osborn, A. R. and Mahmud, T. (2019) ‘Interkingdom Genetic Mix-and-Match to Produce Novel Sunscreens’, ACS Synthetic Biology , 8(11), pp. 2464–2471. doi: 10.1021/acssynbio.9b00352. 3. Sulheim, S. et al. (2020) ‘Enzyme-Constrained Models and Omics Analysis of Streptomyces coelicolor Reveal Metabolic Changes that Enhance Heterologous Production’, iScience , 23(9). doi: 10.1016/j.isci.2020.101525.
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