Related Experiment Video
Updated: Aug 6, 2026

From a Natural Product to Its Biosynthetic Gene Cluster: A Demonstration Using Polyketomycin from Streptomyces diastatochromogenes Tü6028
Published on: January 13, 2017
Structural Basis for Medium-Chain Dehydrogenase/Reductase-Catalyzed Reductive Cyclization in Polycyclic Tetramate
Xiangqian Xie1, Fan Li1, Yanxin Mu1
1State Key Laboratory of Discovery and Utilization of Functional Components in Traditional Chinese Medicine, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, People's Republic of China.
Researchers elucidated the mechanism of a novel enzyme subclass catalyzing reductive cyclizations in polycyclic tetramate macrolactam (PoTeM) biosynthesis. Structural insights reveal hydride-mediated C-C bond formation critical for natural product synthesis.
Area of Science:
- Biochemistry
- Enzymology
- Natural Product Biosynthesis
Background:
- Medium-chain dehydrogenases/reductases (MDRs) typically perform dehydrogenase or reductase functions.
- A unique MDR subclass catalyzes reductive cyclizations via hydride-mediated C-C bond formation in PoTeM biosynthesis.
Purpose of the Study:
- To determine the structural and mechanistic basis of reductive cyclization catalyzed by OX4 and CftD.
- To understand the formation of the third ring in polycyclic tetramate macrolactams (PoTeMs).
Main Methods:
- X-ray crystallography to obtain apo and substrate-bound structures of OX4 and CftD.
- Site-directed mutagenesis to probe the catalytic mechanism.
- Biochemical assays to confirm enzyme function.
Main Results:
- The structures reveal a NADPH-dependent 1,6-reduction followed by C11-C22 bond formation.
- A conserved W260 residue is critical for substrate positioning and enolate intermediate stabilization.
- The catalytic mechanism involves water-mediated protonation and tautomerization to yield the cyclized product.
Conclusions:
- This study provides the first structural and mechanistic insights into this novel cyclase subgroup.
- Findings offer potential for enzyme engineering and the biosynthesis of new natural products.
Related Concept Videos
Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
Loss of Carboxy Group as CO2: Decarboxylation of Malonic Acid Derivatives
Pericyclic Reactions: Introduction
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic rearrangements are...
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Phase I Reactions: Reductive Reactions

![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)