Exploring the mechanism of lipid transfer during biosynthesis of the acidic lipopeptide antibiotic CDA.

The non-ribosomally synthesized lipodepsipeptide CDA belongs to the group of acidic lipopeptide antibiotics, whose members feature a fatty acid side chain that strongly affects their antimicrobial activity. This study elucidates the N-acylation of the N-terminal serine in the CDA peptide chain. This reaction is referred to as lipoinitiation and is shown to be catalyzed by the dissected starter C domain found at the N-terminus of Cda-PSI. The recombinantly produced C domain specifically interacts with 2,3-epoxyhexanoyl-S-ACP and catalyzes the transfer of the fatty acid moiety onto the amino group of PCP-bound serine with high selectivity for both carrier protein bound substrates at the donor and acceptor site.