Side-Chain Macrocyclization in Ahp-Bicyclodepsipeptides Biosynthesis Involves Cytochrome P450-Catalyzed Sequential...

Area of Science:

• Biochemistry
• Organic Chemistry
• Molecular Biology

Background:

• Bicyclodepsipeptides are complex natural products with diverse biological activities.
• The biosynthesis of these molecules often involves intricate enzymatic pathways.
• Formation of N-C bridges in macrocycles presents a significant synthetic challenge.

Purpose of the Study:

• To elucidate the biosynthetic pathway of FR901277 and delmomycin A2.
• To identify and characterize the enzyme responsible for the key macrocyclization step.
• To understand the mechanism of cytochrome P450-catalyzed C-N bond formation.

Main Methods:

• Biosynthetic precursor feeding experiments.
• Enzyme purification and characterization of Dlm16 (a cytochrome P450 monooxygenase).
• Site-directed mutagenesis and structure-function analyses.
• Bioinformatic analysis of Dlm16 homologs.

Main Results:

• Dlm16 catalyzes the N-C bridge formation in FR901277 and delmomycin A2 biosynthesis.
• The mechanism involves sequential ortho-hydroxylation of tyrosine followed by intramolecular C-N coupling.
• Key catalytic residues within Dlm16 were identified.
• Eight additional Dlm16 homologs were characterized, indicating a conserved CYP450 subfamily for C-N bond formation.

Conclusions:

• Nature employs cytochrome P450 monooxygenases for unusual C-N bond formation in cyclodepsipeptide biosynthesis.
• The identified mechanism provides insights into macrocycle construction strategies.
• This work expands the known repertoire of CYP450-catalyzed reactions, specifically direct C-H functionalization for C-N coupling.