α-Ketoglutarate-Dependent Dioxygenase-Catalyzed Macrocyclization in RiPPs.

Area of Science:

• Biochemistry
• Molecular Biology
• Bioorganic Chemistry

Background:

• α-Ketoglutarate-dependent dioxygenases (αKGDs) are known oxidative biocatalysts.
• Their function in ribosomally synthesized and post-translationally modified peptide (RiPP) macrocyclization was previously unknown.
• JmjC domain-containing αKGDs (JMJDs) are frequently found alongside RiPP biosynthetic gene clusters (BGCs).

Purpose of the Study:

• To investigate the role of αKGDs in RiPP macrocyclization.
• To characterize a novel two-component JMJD system involved in RiPP biosynthesis.
• To elucidate the mechanism of oxidative cross-linking in lanthipeptide formation.

Main Methods:

• Bioinformatic analysis of RiPP BGCs to identify co-occurring JMJDs.
• Heterologous reconstitution of the cor BGC from Streptomyces corchorusii.
• Biochemical assays and mechanistic studies to determine enzyme function and reaction pathways.

Main Results:

• A conserved group of class II lanthipeptide BGCs encode a two-component JMJD pair.
• The cor BGC yields the metal-binding lanthipeptide corsin, featuring a methyllanthionine ring and a Cys(S)-Tyr(Cβ) cross-link.
• The CorB-CorD JMJD pair catalyzes oxidative Cys(S)-Tyr(Cβ) cross-linking via a para-quinone methide intermediate, with CorB acting as an essential partner to the catalytic CorD.

Conclusions:

• αKGDs, specifically JMJDs, are novel radical catalysts for RiPP macrocyclization.
• A unique two-component αKGD system involving an active JMJD and an inactive homologue expands the known enzymatic toolkit for RiPP diversification.
• This discovery deepens the understanding of enzymatic strategies in natural product biosynthesis.