Volume 60, Issue 16 pp. 8851-8858
Research Article

One Polyketide Synthase, Two Distinct Products: Trans-Acting Enzyme-Controlled Product Divergence in Calbistrin Biosynthesis

Dr. Hui Tao

Dr. Hui Tao

Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan

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Dr. Takahiro Mori

Dr. Takahiro Mori

Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan

Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657 Japan

PRESTO (Japan) Science and Technology Agency, Kawaguchi, Saitama, 332-0012 Japan

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Xingxing Wei

Xingxing Wei

Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China

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Dr. Yudai Matsuda

Corresponding Author

Dr. Yudai Matsuda

Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China

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Prof. Dr. Ikuro Abe

Corresponding Author

Prof. Dr. Ikuro Abe

Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan

Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657 Japan

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First published: 22 January 2021
Citations: 19

Graphical Abstract

Calbistrin biosynthesis involves an unusual dual-functional polyketide synthase CalA, which synthesizes both of the two structurally distinct moieties of calbistrins. The product divergence is intriguingly controlled by two trans-acting enzymes, a trans-acting enoylreductase CalK and a trans-acting C-methyltransferase CalH, to yield the decalin and polyene portions, respectively.

Abstract

Calbistrins are fungal polyketides consisting of the characteristic decalin and polyene moieties. Although the biosynthetic gene cluster of calbistrin A was recently identified, the pathway of calbistrin A biosynthesis has largely remained uninvestigated. Herein, we investigated the mechanism by which the backbone structures of calbistrins are formed, by heterologous and in vitro reconstitution of the biosynthesis and a structural biological study. Intriguingly, our analyses revealed that the decalin and polyene portions of calbistrins are synthesized by the single polyketide synthase (PKS) CalA, with the aid of the trans-acting enoylreductase CalK and the trans-acting C-methyltransferase CalH, respectively. We also determined that the esterification of the two polyketide parts is catalyzed by the acyltransferase CalD. Our study has uncovered a novel dual-functional PKS and thus broadened our understanding of how fungi synthesize diverse polyketide natural products.

Conflict of interest

The authors declare no conflict of interest.

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