Iminium Catalysis in Natural Diels-Alderase.

Zuodong Sun, Xin Zang, Qingyang Zhou, Masao Ohashi, K N Houk, Jiahai Zhou, Yi Tang

Abstract read

In one paragraph

Article in Nature catalysis, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.

0numbers the graph read from it

0cells of the map it votes in

3citing papers in PubMed

–field-weighted citation impact

1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

3 citing papers in PubMed.

High-entropy photocatalyst enabling collaborative cascade C-N coupling for converting benzyl alcohol to imine.Nature communications · 2026
Article
Biosynthesis of the 5-Isoxazolidinone-Containing Hexacyclic Structure of Parnafungin.Journal of the American Chemical Society · 2025
Article
Uncovering a novel biosynthetic gene cluster for sordarin through genome mining in the fungus Talaromyces adpressus.Bioresources and bioprocessing · 2025
Article

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

7 authors.

Zuodong SunDepartment of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States.

Xin ZangDepartment of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States.

Qingyang ZhouDepartment of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States.

Masao OhashiDepartment of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States.

K N HoukDepartment of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States.

Jiahai ZhouKey Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.

Yi TangDepartment of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States.

Funding

Biosynthesis and Enzymology of Antifungal Natural Products - R01AI141481R01AI141481 · NIAID · UNIVERSITY OF CALIFORNIA LOS ANGELES · PI GARG, NEIL K, HOUK, KENDALL N · 2019 to 2023

$2.8M

NIAID NIH HHS R01 AI141481

6 · The paper itself

Abstract

Iminium-catalyzed cycloaddition is one of the most prominent examples of organocatalysis, yet a biological counterpart has not been reported despite the wide-spread occurrence of iminium adducts in enzymes. Here, we present biochemical, structural, and computational evidence for iminium catalysis by the natural Diels-Alderase SdnG that catalyzes norbornene formation in sordarin biosynthesis. A Schiff base adduct between the ε-nitrogen of active site K127 and the aldehyde group of the enal dienophile was revealed by structural analysis and captured under catalytic conditions via borohydride reduction. This Schiff base adduct positions the substrate into near-attack conformation and decreases the transition state barrier of Diels-Alder cyclization by 8.3 kcal/mol via dienophile activation. A hydrogen bond network consisting of a catalytic triad is proposed to facilitate proton transfer required for iminium formation. This work establishes a new mode of catalysis for Diels-Alderases and points the way to the design of novel iminium based (bio)catalysts.

Identifiers

PMID40881614

DOI10.1038/s41929-025-01294-w

PMCPMC12381789

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.