AvmM catalyses macrocyclization through dehydration/Michael-type addition in alchivemycin A biosynthesis.

Area of Science:

• Biochemistry
• Natural Product Biosynthesis
• Enzymology

Background:

• Macrocyclization is crucial for creating bioactive natural products.
• Nature employs diverse enzymatic strategies for macrocycle formation.
• Alchivemycin A is a bioactive natural product containing a macrocyclic core.

Purpose of the Study:

• To identify and characterize the enzyme responsible for macrocyclization in alchivemycin A biosynthesis.
• To elucidate the mechanism of macrocycle formation catalyzed by the enzyme AvmM.
• To uncover novel macrocyclization strategies in natural product biosynthesis.

Main Methods:

• Gene deletion studies in vivo to confirm enzyme function.
• In vitro biochemical assays to analyze enzyme activity.
• Isotope labeling experiments to trace reaction pathways.
• Crystallography, DFT calculations, and MD simulations for mechanistic insights.

Main Results:

• Identification and characterization of the enzyme AvmM.
• AvmM catalyzes a tandem dehydration and Michael-type addition reaction.
• The enzyme constructs the 16-membered macrocyclic scaffold of alchivemycin A.
• Mechanistic studies revealed substrate-assisted catalysis involving a tenuazonic acid-like moiety.

Conclusions:

• AvmM employs a novel enzymatic strategy for macrocyclization.
• This study reveals a previously uncharacterized pathway in natural product biosynthesis.
• The findings expand our understanding of enzymatic macrocycle formation.