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Hopiavuori A, McKinnie SMK. Algal Kainoid Synthases Exhibit Substrate-Dependent Hydroxylation and Cyclization Activities. ACS Chem Biol 2023; 18:2457-2463. [PMID: 38047879 PMCID: PMC10728896 DOI: 10.1021/acschembio.3c00596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/05/2023]
Abstract
FeII/α-ketoglutarate-dependent dioxygenases (Fe/αKG) make up a large enzyme family that functionalize C-H bonds on diverse organic substrates. Although Fe/αKG homologues catalyze an array of chemically useful reactions, hydroxylation typically predominates. Microalgal DabC uniquely forms a novel C-C bond to construct the bioactive pyrrolidine ring in domoic acid biosynthesis; however, we have identified that this kainoid synthase exclusively performs a stereospecific hydroxylation reaction on its cis substrate regioisomer. Mechanistic and kinetic analyses with native and alternative substrates identified a 20-fold rate increase in DabC radical cyclization over β-hydroxylation with no observable 1,5-hydrogen atom transfer. Moreover, this dual activity was conserved among macroalgal RadC1 and KabC homologues and provided insight into substrate recognition and reactivity trends. Investigation of this substrate-dependent chemistry improves our understanding of kainoid synthases and their biocatalytic application.
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Affiliation(s)
- Austin
R. Hopiavuori
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Shaun M. K. McKinnie
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
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Nishizawa S, Ouchi H, Suzuki H, Ohnishi T, Sasaki S, Oyagi Y, Kanakogi M, Matsumura Y, Nakagawa S, Asakawa T, Egi M, Inai M, Yoshimura F, Takita R, Kan T. Total synthesis of (-)-domoic acid, a potent ionotropic glutamate receptor agonist and the key compound in oceanic harmful algal blooms. Org Biomol Chem 2023; 21:1653-1656. [PMID: 36723220 DOI: 10.1039/d2ob02325c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The stereo-controlled total synthesis of (-)-domoic acid is described. The critical construction of the C1'-C2' Z-configuration was accomplished by taking advantage of an unsaturated lactam structure. The side chain fragment was introduced in the final stages of synthesis through a modified Julia-Kocieński reaction, aiming for its efficient derivatization.
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Affiliation(s)
- Shigeru Nishizawa
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Hitoshi Ouchi
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Hiroto Suzuki
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Takuma Ohnishi
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Shingo Sasaki
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Yu Oyagi
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Masaki Kanakogi
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Yoshitaka Matsumura
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Shunsuke Nakagawa
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Tomohiro Asakawa
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Masahiro Egi
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Makoto Inai
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Fumihiko Yoshimura
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Ryo Takita
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
| | - Toshiyuki Kan
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
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Domoic acid biosynthesis in the red alga Chondria armata suggests a complex evolutionary history for toxin production. Proc Natl Acad Sci U S A 2022; 119:2117407119. [PMID: 35110408 PMCID: PMC8833176 DOI: 10.1073/pnas.2117407119] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2021] [Indexed: 12/04/2022] Open
Abstract
Originally isolated from the red alga Chondria armata, domoic acid (DA) is best known as a potent marine neurotoxin produced by oceanic harmful algal blooms of planktonic diatoms. Sequencing efforts to date of kainoid-producing red algae have focused exclusively on a closely related molecule, kainic acid, leaving a gap in the understanding of DA biosynthesis in red algae and its evolutionary linkage to diatoms. Here, we present the phylogenetic and biochemical investigation of DA biosynthesis in C. armata. This work demonstrates the high synteny of DA biosynthetic genes between relatively distant taxonomic groups of algae and suggests a complex evolutionary history for DA biosynthesis involving gene transfer and neofunctionalization. Domoic acid (DA), the causative agent of amnesic shellfish poisoning, is produced by select organisms within two distantly related algal clades: planktonic diatoms and red macroalgae. The biosynthetic pathway to isodomoic acid A was recently solved in the harmful algal bloom–forming diatom Pseudonitzschia multiseries, establishing the genetic basis for the global production of this potent neurotoxin. Herein, we sequenced the 507-Mb genome of Chondria armata, the red macroalgal seaweed from which DA was first isolated in the 1950s, identifying several copies of the red algal DA (rad) biosynthetic gene cluster. The rad genes are organized similarly to the diatom DA biosynthesis cluster in terms of gene synteny, including a cytochrome P450 (CYP450) enzyme critical to DA production that is notably absent in red algae that produce the simpler kainoid neurochemical, kainic acid. The biochemical characterization of the N-prenyltransferase (RadA) and kainoid synthase (RadC) enzymes support a slightly altered DA biosynthetic model in C. armata via the congener isodomoic acid B, with RadC behaving more like the homologous diatom enzyme despite higher amino acid similarity to red algal kainic acid synthesis enzymes. A phylogenetic analysis of the rad genes suggests unique origins for the red macroalgal and diatom genes in their respective hosts, with native eukaryotic CYP450 neofunctionalization combining with the horizontal gene transfer of N-prenyltransferases and kainoid synthases to establish DA production within the algal lineages.
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Abstract
A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as asporychalasin from Aspergillus oryzae.
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Affiliation(s)
- Robert A Hill
- School of Chemistry, Glasgow University, Glasgow, G12 8QQ, UK.
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