Fig. 3: Combined extracted ion chromatographs (EIC) of enduracidin a and b analogues from LC-HRMS analysis of extracts from primary S. fungicidicus strains (F1-10) used in this study (normalized to 100%), and tandem mass characterization of 2a.
From: Gene editing enables rapid engineering of complex antibiotic assembly lines
a LC-HRMS comparison between CRISPR-Cas9 editing and conventional gene complementation methods for introducing subdomain swaps. The F1a (Swap 1-complement) complementation strain produces mostly 1a & 1b, whereas the CRISPR-Cas9 edited strain S. fungicidicus F1 (Swap 1) produces Ser-containing enduracidins 2a & 2b. b LC-HRMS analysis of all productive mutants that generate new enduracidin analogues. c LC-HRMS/MS analysis of 1a and 2a confirms that Thr has been replaced with Ser in compound 2a. Fragment ions containing residue 2 are 14 mass units higher in 1a compared with 2a (methyl group of Thr). Loss of residue 2 results in fragment ions with identical m/z values between 1a and 2a.
