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Liu T, Mazmouz R, Ongley SE, Chau R, Pickford R, Woodhouse JN, Neilan BA. Directing the Heterologous Production of Specific Cyanobacterial Toxin Variants. ACS Chem Biol 2017; 12:2021-2029. [PMID: 28570054 DOI: 10.1021/acschembio.7b00181] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Microcystins are globally the most commonly occurring freshwater cyanotoxins, causing acute poisoning and chronically inducing hepatocellular carcinoma. However, the detection and toxicological study of microcystins is hampered by the limited availability and high cost of pure toxin standards. Biosynthesis of microcystin variants in a fast-growing heterologous host offers a promising method of achieving reliable and economically viable alternative to isolating toxin from slow-growing cyanobacterial cultures. Here, we report the heterologous expression of recombinant microcystin synthetases in Escherichia coli to produce [d-Asp3]microcystin-LR and microcystin-LR. We assembled a 55 kb hybrid polyketide synthase/nonribosomal peptide synthetase gene cluster from Microcystis aeruginosa PCC 7806 using Red/ET recombineering and replaced the native promoters with an inducible PtetO promoter to yield microcystin titers superior to M. aeruginosa. The expression platform described herein can be tailored to heterologously produce a wide variety of microcystin variants, and potentially other cyanobacterial natural products of commercial relevance.
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Affiliation(s)
- Tianzhe Liu
- School
of Biotechnology and Biomolecular Sciences, The University of New South Wales, New South Wales 2052, Sydney, Australia
| | - Rabia Mazmouz
- School
of Biotechnology and Biomolecular Sciences, The University of New South Wales, New South Wales 2052, Sydney, Australia
- School
of Environmental and Life Sciences, The University of Newcastle, New
South Wales 2308, Callaghan, Australia
| | - Sarah E. Ongley
- School
of Biotechnology and Biomolecular Sciences, The University of New South Wales, New South Wales 2052, Sydney, Australia
- School
of Environmental and Life Sciences, The University of Newcastle, New
South Wales 2308, Callaghan, Australia
| | - Rocky Chau
- School
of Biotechnology and Biomolecular Sciences, The University of New South Wales, New South Wales 2052, Sydney, Australia
| | - Russell Pickford
- Bioanalytical
Mass Spectrometry Facility, The University of New South Wales, New
South Wales 2052, Sydney, Australia
| | - Jason N. Woodhouse
- School
of Biotechnology and Biomolecular Sciences, The University of New South Wales, New South Wales 2052, Sydney, Australia
- Leibniz
Institute of Freshwater Ecology and Inland Fisheries (IGB), Experimental Limnology, 12587, Berlin, Germany
| | - Brett A. Neilan
- School
of Biotechnology and Biomolecular Sciences, The University of New South Wales, New South Wales 2052, Sydney, Australia
- School
of Environmental and Life Sciences, The University of Newcastle, New
South Wales 2308, Callaghan, Australia
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Zemskov I, Altaner S, Dietrich DR, Wittmann V. Total Synthesis of Microcystin-LF and Derivatives Thereof. J Org Chem 2017; 82:3680-3691. [PMID: 28294610 DOI: 10.1021/acs.joc.7b00175] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Microcystins (MCs) are highly toxic natural products which are produced by cyanobacteria. They can be released to the water during harmful algal blooms and are a serious threat to animals and humans. Described is the total synthesis of the cyanotoxin microcystin-LF (MC-LF, 1a) and two derivatives thereof. Deuterated derivative 1b is of interest as an internal standard during MC quantification in biological samples by mass spectrometry and alkyne-labeled 1c can be employed for toxin derivatization by click chemistry with an azide-containing reporter molecule or as an activity-based probe to identify interaction partners. Application of tert-butyl ester protecting groups for erythro-β-d-methylaspartic acid and γ-d-glutamic acid were key for an isomerization-free synthesis. The analytical data of synthetic MC-LF were identical to those of an authentic sample of the natural product. All derivatives 1a-c were determined to be potent inhibitors of protein phosphatase-1 with similar activity.
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Affiliation(s)
- Ivan Zemskov
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz , 78457 Konstanz, Germany
| | - Stefan Altaner
- Department of Biology and Graduate School Biological Sciences (GBS), University of Konstanz , 78457 Konstanz, Germany
| | - Daniel R Dietrich
- Department of Biology and Graduate School Biological Sciences (GBS), University of Konstanz , 78457 Konstanz, Germany
| | - Valentin Wittmann
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz , 78457 Konstanz, Germany
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