Characterisation of the modification enzymes involved in the biosynthesis of two novel lanthipeptides

Carolin von Lupin, Michelle Quezada, Rabia Mazmouz, Brett Neilan

 

ABSTRACT PRESENTED AT: GRC – Natural Products and Bioactive Compounds

Ribosomally synthesised and post-translationally modified peptides (RiPPs) present a large class of natural products. Lanthipeptides, or lantibiotics, are the most abundant group of RiPPs that generally exhibit antibacterial activity, which makes them attractive for the pharmaceutical and food industry. The steps of lanthipeptide biosynthesis include amino acid residue dehydration, peptide cyclisation and proteolysis in order to generate the biologically active compound. These reactions are performed by distinct enzymes, which are encoded within the biosynthetic gene cluster of lantibiotics.

Here, we report the discovery of two novel lanthipeptides and their biosynthesis genes from Pseudoalteromonas sp. HMSA03. The aim of this study is to characterise the activity, both in vivo and in vitro, of the modification enzymes that are required for the production of the mature lanthipeptides. His-tagged prepeptides PamA1 and PamA2 were co-expressed with dehydratase PamB and cyclase PamC using Escherichia coli as a heterologous host. The modified prepeptides were purified by affinity chromatography, analysed by mass spectrometry and subsequently cleaved in vitro using heterologously expressed PamP for final peptide maturation. The resulting lanthipeptides Pam1 and Pam2 will be analysed regarding their structure and bioactivity.

This study provides a combined in vivo and in vitro approach for lanthipeptide production.  This can be utilised as an alternative heterologous expression system for unamenable, lower-yield native hosts and as a platform for bioactive peptide pathway engineering. The results of this study will give insight into lantibiotic biosynthesis and will reveal the bioactivity and structure of two novel lanthipeptides.

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