Enzymatic Basis of ‘Hybridity’ in Thiomarinol Biosynthesis

摘要

Thiomarinol is a naturally occurring double-headed antibiotic that is highly potent against methicillin-resistant Staphylococcus aureus. Its structure comprises two antimicrobial sub-components, marinolic acid and holothin, linked by an amide bond. TmlU was thought to be the sole enzyme responsible for this amide bond formation. Contrary to this idea, we show that TmlU acts as a CoA ligase that activates marinolic acid as its thioester before it is processed by the acetyltransferase HolE to catalyze the amidation. TmlU prefers complex acyl acids as substrates, whereas HolE is relatively promiscuous, accepting a range of acyl-CoA and amine substrates. Our results provide detailed biochemical information on thiomarinol biosynthesis, and evolutionary insight regarding how the marinolic acid and holothin pathways converge to generate this potent hybrid antibiotic. This work also demonstrates the potential of TmlU/HolE enzymes as engineering tools to generate new “hybrid” molecules.