Sesbanimide R, a novel cytotoxic polyketide produced by magnetotactic bacteria [article]

Ram Prasad Awal, Patrick A. Haack, Chantal Denise Bader, Cornelius N. Riese, Dirk Schüler, Rolf Müller
2020 bioRxiv   pre-print
Genomic information from various magnetotactic bacteria suggested that besides their common ability to form magnetosomes they potentially also represent a source of bioactive natural products. By using targeted deletion and transcriptional activation, we connected a large biosynthetic gene cluster (BGC) of the trans -AT PKS type to the biosynthesis of a novel polyketide in the alphaproteobacterium Magnetospirillum gryphiswaldense. Structure elucidation by mass spectrometry and NMR revealed that
more » ... this secondary metabolite resembles sesbanimides which were very recently reported from other taxa. However, sesbanimide R exhibits an additional arginine moiety the presence of which reconciles inconsistencies in the previously proposed sesbanimide biosynthesis pathway when comparing the chemical structure and the potential biochemistry encoded in the BGC. In contrast to sesbanimides D, E and F, we were able to assign the stereocenter of the arginine moiety experimentally and two of the remaining three stereocenters by predictive biosynthetic tools. Sesbanimide R displayed strong cytotoxic activity against several carcinoma cell lines.
doi:10.1101/2020.12.22.424014 fatcat:3knlar3lbzdl5cm37nes4yg7ju