(188r) Rapid Discovery of Lanthipeptides and Glycocins through Pathway Refactoring in Escherichia coli

Ribosomally synthesized post-translationally modified peptides (RiPPs) constitute an emerging family of natural products with various structural features and bioactivities. Both lanthipeptides and glycocins are groups of RiPPs with various antimicrobial activities, representing promising sources for new antibiotics. For example, nisin, a representative lanthipeptide, has been used in industry for controlling food-borne pathogens for more than 40 years. To date, more than a hundred lanthipeptides have been discovered and some of them are under clinical trials. In comparison, glycocins are largely underexplored and only six members have been identified. However, sublancin, one of the most well characterized glycocins, exhibited antimicrobial activities to multiple pathogens of interest including methicillin–resistant Streptococcus aureus (MRSA). Here we sought to use a synthetic biology approach based on the pathway refactoring strategy we previously developed to rapidly discover new lanthipeptides and glycocins. Two novel lanthipeptides including one Class IV lanthipeptide with an unusual ring topology were successfully discovered. In addition, four novel glycocins were also discovered and one of them, which belongs to the enterocin 96-type glycocins, was unprecedentedly di-glucosylated on a single serine. Further bioactivity characterization of glycocins revealed that three of them exhibit narrower antimicrobial spectrum than sublancin, even though they share similar topology and modification. Further evaluation of their bioactivities with free glucose at high concentrations suggested that their antimicrobial mechanisms might be both glycocin- and species-specific. Overall, these lanthipeptides and glycocins with distinct features have significantly broadened our knowledge on both lanthipeptides and glycocins and may lead to the discovery of new classes of antibiotics.