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Nguyen N, Forstater JH, McIntosh JA. Decarboxylation in Natural Products Biosynthesis. JACS AU 2024; 4:2715-2745. [PMID: 39211618 PMCID: PMC11350588 DOI: 10.1021/jacsau.4c00425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Revised: 07/01/2024] [Accepted: 07/05/2024] [Indexed: 09/04/2024]
Abstract
Decarboxylation reactions are frequently found in the biosynthesis of primary and secondary metabolites. Decarboxylase enzymes responsible for these transformations operate via diverse mechanisms and act on a large variety of substrates, making them appealing in terms of biotechnological applications. This Perspective focuses on the occurrence of decarboxylation reactions in natural product biosynthesis and provides a perspective on their applications in biocatalysis for fine chemicals and pharmaceuticals.
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Baral B, Matroodi S, Siitonen V, Thapa K, Akhgari A, Yamada K, Nuutila A, Metsä-Ketelä M. Co-factor independent oxidases ncnN and actVA-3 are involved in the dimerization of benzoisochromanequinone antibiotics in naphthocyclinone and actinorhodin biosynthesis. FEMS Microbiol Lett 2023; 370:fnad123. [PMID: 37989784 PMCID: PMC10697411 DOI: 10.1093/femsle/fnad123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 10/19/2023] [Accepted: 11/20/2023] [Indexed: 11/23/2023] Open
Abstract
Streptomyces produce complex bioactive secondary metabolites with remarkable chemical diversity. Benzoisochromanequinone polyketides actinorhodin and naphthocyclinone are formed through dimerization of half-molecules via single or double carbon-carbon bonds, respectively. Here we sequenced the genome of S. arenae DSM40737 to identify the naphthocyclinone gene cluster and established heterologous production in S. albus J1074 by utilizing direct cluster capture techniques. Comparative sequence analysis uncovered ncnN and ncnM gene products as putative enzymes responsible for dimerization. Inactivation of ncnN that is homologous to atypical co-factor independent oxidases resulted in the accumulation of fogacin, which is likely a reduced shunt product of the true substrate for naphthocyclinone dimerization. In agreement, inactivation of the homologous actVA-3 in S. coelicolor M145 also led to significantly reduced production of actinorhodin. Previous work has identified the NAD(P)H-dependent reductase ActVA-4 as the key enzyme in actinorhodin dimerization, but surprisingly inactivation of the homologous ncnM did not abolish naphthocyclinone formation and the mutation may have been complemented by an endogenous gene product. Our data suggests that dimerization of benzoisochromanequinone polyketides require two-component reductase-oxidase systems.
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Affiliation(s)
- Bikash Baral
- Department of Life Technologies, University of Turku, FIN-20014 Turku, Finland
| | - Soheila Matroodi
- Department of Life Technologies, University of Turku, FIN-20014 Turku, Finland
- Laboratory of Biotechnology, Department of Marine Biology, Faculty of Marine Science and Oceanography, University of Marine Science and Technology, 64199-34619 Khorramshahr, Iran
| | - Vilja Siitonen
- Department of Life Technologies, University of Turku, FIN-20014 Turku, Finland
| | - Keshav Thapa
- Department of Life Technologies, University of Turku, FIN-20014 Turku, Finland
| | - Amir Akhgari
- Department of Life Technologies, University of Turku, FIN-20014 Turku, Finland
| | - Keith Yamada
- Department of Life Technologies, University of Turku, FIN-20014 Turku, Finland
| | - Aleksi Nuutila
- Department of Life Technologies, University of Turku, FIN-20014 Turku, Finland
| | - Mikko Metsä-Ketelä
- Department of Life Technologies, University of Turku, FIN-20014 Turku, Finland
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Activation of Secondary Metabolism in Red Soil-Derived Streptomycetes via Co-Culture with Mycolic Acid-Containing Bacteria. Microorganisms 2021; 9:microorganisms9112187. [PMID: 34835313 PMCID: PMC8622677 DOI: 10.3390/microorganisms9112187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/15/2021] [Accepted: 10/15/2021] [Indexed: 11/25/2022] Open
Abstract
Our previous research has demonstrated a promising capacity of streptomycetes isolated from red soils to produce novel secondary metabolites, most of which, however, remain to be explored. Co-culturing with mycolic acid-containing bacteria (MACB) has been used successfully in activating the secondary metabolism in Streptomyces. Here, we co-cultured 44 strains of red soil-derived streptomycetes with four MACB of different species in a pairwise manner and analyzed the secondary metabolites. The results revealed that each of the MACB strains induced changes in the metabolite profiles of 35–40 streptomycetes tested, of which 12–14 streptomycetes produced “new” metabolites that were not detected in the pure cultures. Moreover, some of the co-cultures showed additional or enhanced antimicrobial activity compared to the pure cultures, indicating that co-culture may activate the production of bioactive compounds. From the co-culture-induced metabolites, we identified 49 putative new compounds. Taking the co-culture of Streptomyces sp. FXJ1.264 and Mycobacterium sp. HX09-1 as a case, we further explored the underlying mechanism of co-culture activation and found that it most likely relied on direct physical contact between the two living bacteria. Overall, our results verify co-culture with MACB as an effective approach to discover novel natural products from red soil-derived streptomycetes.
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Stunkard LM, Kick BJ, Lohman JR. Structures of LnmK, a Bifunctional Acyltransferase/Decarboxylase, with Substrate Analogues Reveal the Basis for Selectivity and Stereospecificity. Biochemistry 2021; 60:365-372. [PMID: 33482062 DOI: 10.1021/acs.biochem.0c00893] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
LnmK stereospecifically accepts (2R)-methylmalonyl-CoA, generating propionyl-S-acyl carrier protein to support polyketide biosynthesis. LnmK and its homologues are the only known enzymes that carry out a decarboxylation (DC) and acyl transfer (AT) reaction in the same active site as revealed by structure-function studies. Substrate-assisted catalysis powers LnmK, as decarboxylation of (2R)-methylmalonyl-CoA generates an enolate capable of deprotonating active site Tyr62, and the Tyr62 phenolate subsequently attacks propionyl-CoA leading to a propionyl-O-LnmK acyl-enzyme intermediate. Due to the inherent reactivity of LnmK and methylmalonyl-CoA, a substrate-bound structure could not be obtained. To gain insight into substrate specificity, stereospecificity, and catalytic mechanism, we determined the structures of LnmK with bound substrate analogues that bear malonyl-thioester isosteres where the carboxylate is represented by a nitro or sulfonate group. The nitro-bearing malonyl-thioester isosteres bind in the nitronate form, with specific hydrogen bonds that allow modeling of the (2R)-methylmalonyl-CoA substrate and rationalization of stereospecificity. The sulfonate isosteres bind in multiple conformations, suggesting the large active site of LnmK allows multiple binding modes. Considering the smaller malonyl group has more conformational freedom than the methylmalonyl group, we hypothesized the active site can entropically screen against catalysis with the smaller malonyl-CoA substrate. Indeed, our kinetic analysis reveals malonyl-CoA is accepted at 1% of the rate of methylmalonyl-CoA. This study represents another example of how our nitro- and sulfonate-bearing methylmalonyl-thioester isosteres are of use for elucidating enzyme-substrate binding interactions and revealing insights into catalytic mechanism. Synthesis of a larger panel of analogues presents an opportunity to study enzymes with complicated structure-function relationships such as acyl-CoA carboxylases, trans-carboxytransferases, malonyltransferases, and β-ketoacylsynthases.
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Affiliation(s)
- Lee M Stunkard
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Benjamin J Kick
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jeremy R Lohman
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, United States.,Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907, United States
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Walker PD, Weir ANM, Willis CL, Crump MP. Polyketide β-branching: diversity, mechanism and selectivity. Nat Prod Rep 2021; 38:723-756. [PMID: 33057534 DOI: 10.1039/d0np00045k] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Covering: 2008 to August 2020 Polyketides are a family of natural products constructed from simple building blocks to generate a diverse range of often complex chemical structures with biological activities of both pharmaceutical and agrochemical importance. Their biosynthesis is controlled by polyketide synthases (PKSs) which catalyse the condensation of thioesters to assemble a functionalised linear carbon chain. Alkyl-branches may be installed at the nucleophilic α- or electrophilic β-carbon of the growing chain. Polyketide β-branching is a fascinating biosynthetic modification that allows for the conversion of a β-ketone into a β-alkyl group or functionalised side-chain. The overall transformation is catalysed by a multi-protein 3-hydroxy-3-methylglutaryl synthase (HMGS) cassette and is reminiscent of the mevalonate pathway in terpene biosynthesis. The first step most commonly involves the aldol addition of acetate to the electrophilic carbon of the β-ketothioester catalysed by a 3-hydroxy-3-methylglutaryl synthase (HMGS). Subsequent dehydration and decarboxylation selectively generates either α,β- or β,γ-unsaturated β-alkyl branches which may be further modified. This review covers 2008 to August 2020 and summarises the diversity of β-branch incorporation and the mechanistic details of each catalytic step. This is extended to discussion of polyketides containing multiple β-branches and the selectivity exerted by the PKS to ensure β-branching fidelity. Finally, the application of HMGS in data mining, additional β-branching mechanisms and current knowledge of the role of β-branches in this important class of biologically active natural products is discussed.
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Affiliation(s)
- P D Walker
- Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - A N M Weir
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - C L Willis
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - M P Crump
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
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Lohman JR, Shen B. The LnmK Bifunctional Acyltransferase/Decarboxylase Specifying (2 R)-Methylmalonyl-CoA and Employing Substrate-Assisted Catalysis for Polyketide Biosynthesis. Biochemistry 2020; 59:4143-4147. [PMID: 33095002 DOI: 10.1021/acs.biochem.0c00749] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We previously showed that the bifunctional LnmK acyltransferase/decarboxylase (AT/DC) catalyzed the formation of a propionyl-S-acyl carrier protein (ACP) from methylmalonyl-CoA, but its substrate specificity to (2S)-, (2R)-, or (2RS)-methylmalonyl CoA was not known. We subsequently revealed that LnmK AT and DC activities share the same active site, employing a Tyr as the catalytic residue for AT, but failed to identify a general base within the vicinity of the active site for LnmK catalysis. We now show that (i) LnmK specifies (2R)-methylmalonyl-CoA and (ii) the AT and DC activities are coupled, featuring substrate-assisted catalysis via the enolate to account for the missing general base within the LnmK active site. LnmK and its homologues are the only bifunctional AT/DC enzymes known to date and are widespread. These findings, therefore, enrich PKS chemistry and enzymology. Since only the (2S)-methylmalonyl-CoA enantiomer has been established previously as a substrate for polyketide biosynthesis by PKSs, we now establish a role for both (2R)- and (2S)-methylmalonyl-CoA in polyketide biosynthesis, and (2R)-methylmalonyl-CoA should be considered as a substrate in future efforts for engineered production of polyketides by combinatorial biosynthesis or synthetic biology strategies in model hosts.
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Affiliation(s)
- Jeremy R Lohman
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, United States
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Malico AA, Nichols L, Williams GJ. Synthetic biology enabling access to designer polyketides. Curr Opin Chem Biol 2020; 58:45-53. [PMID: 32758909 DOI: 10.1016/j.cbpa.2020.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 05/08/2020] [Accepted: 06/11/2020] [Indexed: 12/18/2022]
Abstract
The full potential of polyketide discovery has yet to be reached owing to a lack of suitable technologies and knowledge required to advance engineering of polyketide biosynthesis. Recent investigations on the discovery, enhancement, and non-natural use of these biosynthetic gene clusters via computational biology, metabolic engineering, structural biology, and enzymology-guided approaches have facilitated improved access to designer polyketides. Here, we discuss recent successes in gene cluster discovery, host strain engineering, precursor-directed biosynthesis, combinatorial biosynthesis, polyketide tailoring, and high-throughput synthetic biology, as well as challenges and outlooks for rapidly generating useful target polyketides.
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Affiliation(s)
- Alexandra A Malico
- Department of Chemistry, NC State University, Raleigh, NC, 27695, United States
| | - Lindsay Nichols
- Department of Chemistry, NC State University, Raleigh, NC, 27695, United States
| | - Gavin J Williams
- Department of Chemistry, NC State University, Raleigh, NC, 27695, United States; Comparative Medicine Institute, NC State University, Raleigh, NC, 27695, United States.
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Katsuyama Y. Mining novel biosynthetic machineries of secondary metabolites from actinobacteria. Biosci Biotechnol Biochem 2019; 83:1606-1615. [DOI: 10.1080/09168451.2019.1606700] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
ABSTRACT
Secondary metabolites produced by actinobacteria have diverse structures and important biological activities, making them a useful source of drug development. Diversity of the secondary metabolites indicates that the actinobacteria exploit various chemical reactions to construct a structural diversity. Thus, studying the biosynthetic machinery of these metabolites should result in discovery of various enzymes catalyzing interesting and useful reactions. This review summarizes our recent studies on the biosynthesis of secondary metabolites from actinobacteria, including the biosynthesis of nonproteinogenic amino acids used as building blocks of nonribosomal peptides, the type II polyketide synthase catalyzing polyene scaffold, the nitrous acid biosynthetic pathway involved in secondary metabolite biosynthesis and unique cytochrome P450 catalyzing nitrene transfer. These findings expand the knowledge of secondary metabolite biosynthesis machinery and provide useful tools for future bioengineering.
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Affiliation(s)
- Yohei Katsuyama
- Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Japan
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