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. 2016 Mar 18;55(13):4220-5.
doi: 10.1002/anie.201511348. Epub 2016 Mar 1.

Chemoreactive Natural Products that Afford Resistance Against Disparate Antibiotics and Toxins

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Chemoreactive Natural Products that Afford Resistance Against Disparate Antibiotics and Toxins

Lin Du et al. Angew Chem Int Ed Engl. .

Abstract

Microorganisms use chemical inactivation strategies to circumvent toxicity caused by many types of antibiotics. Yet in all reported cases, this approach is limited to enzymatically facilitated mechanisms that each target narrow ranges of chemically related scaffolds. The fungus-derived shikimate analogues, pericoxide and pericosine A, were identified as chemoreactive natural products that attenuate the antagonistic effects of several synthetic and naturally derived antifungal agents. Experimental and computational studies suggest that pericoxide and pericosine A readily react via SN 2' mechanisms against a variety of nucleophilic substances under both in vitro aqueous and in situ co-culture conditions. Many of the substitution products from this reaction were highly stable and exhibited diminished toxicities against environmental fungal isolates, including the Tolypocladium sp. strain that produced pericoxide and pericosine A.

Keywords: antibiotic resistance; co-culture; fungi; isotope labeling; natural products; substitution reactions.

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Figures

Figure 1
Figure 1
(A) Structures for maximiscin (1) and its rearrangement artifact, isomaximiscin (2). 13C isotope incorporation (accomplished by feeding [U-13C6]-D-glucose to the fungus and analyzing the resulting 1JC-C coupling values) was used to monitor the origin of the C-2′ position in 1 and the corresponding C-2 position for the key chemical degradation product, pericosine C (3). (B) Experimental and calculated ECD spectra (TD-DFT) were used to resolve the absolute configurations of 1 and 2. The illustrated 13C labeling and ECD methods developed during the structure revision process for 1 were instrumental for understanding the structures and mechanisms of formation for the compounds described in this study. Details of the rationale applied to the structure revision of 1, along with the experimental methods created for this purpose are provided in the supporting information accompanying this report.
Figure 2
Figure 2
UPLC-ESIMSn profiling of selected secondary metabolites produced by Tolypocladium sp. T1 (C and D) and coculture of T1 with Penicillium sp. P1 (E and F) and P2 (G and H). (A and B) Proposed MSn splitting patterns for shikimate substitution products. Selected ion traces for m/z 450.2, 464.2 and 507.2 are shown in C, E, and G, respectively. Their corresponding MSn spectra are shown in D, F, and H (Figure 2H shows the MSn spectrum of 6, which is identical to that of 7). *MS signals of unknown substances.
Figure 3
Figure 3
Substrate transformation products obtained from Tolypocladium sp. T1. The 13C-labeling patterns for the substrate-shikimate substitution products were generated by feeding T1 with [U-13C6]-D-glucose.
Figure 4
Figure 4
Electrophilic natural products from fungus T1. (A) 13C-labeling patterns for 10 and 11 generated by feeding T1 [U-13C6]-D-glucose with NaCl present in the culture medium. (B) Selectivity and yields for the SN2′ coupling of 12 with 10 and 11. The reaction rates of selected model substrates (13 and 17) were tested and the results provided in the SI (Figure S127).
Figure 5
Figure 5
Calculated transition states and relative free energies of activation for the reactions of 10 and 11 with 1-hydroxy-3-methyl-2-oxo-1,2-dihydropyridin-4-olate (23). aB3LYP/6-31G(d) was used to determine TS structures; free energies were obtained from single point calculations by M06-2X and MP2 (in parenthesis) methods and 6-311++G(d,p) basis set.
Figure 6
Figure 6
(A) Comparison of the antifungal efficacy of the shikimate-substrate substitution products (1, 4, 6, 7, 14, and 18) and their corresponding parent compounds (8, 9, 12, 13, and 17) against a panel of test fungi (T1–T4, P1–P4, and A1). (B) Co-treatment of fungi with 11 and 13 (fungi T1, T2, P1, P4, and A1) reduced the antifungal efficacy of 13. (C) Effect of supplemental NaNO3 in test medium on the antifungal efficacy of 8 and 13 against T1. Media types: PDB, potato dextrose broth; PDB-N, PDB plus 2 g/L NaNO3; PDB 8:2, mixture of centrifuged broth of T1 grown in PDB for 5 days with fresh PDB at the ratio of 8:2; PDB-N 8:2, mixture of centrifuged broth of T1 grown in PDB-N for 5 days with fresh PDB at the ratio of 8:2.
Scheme 1
Scheme 1
Chemoassay-guided identification of shikimate analogues 10 and 11. The culture broth of T1 was subjected separately to dialysis and partitioning and treated with the P1-derived metabolite 8. LAESIMS was used to track the presence of 10 and 11 by monitoring the formation of 4 (m/z 464 Da).

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References

    1. Charlop-Powers Z, Owen JG, Reddy BVB, Ternei MA, Brady SF. Proc Natl Acad Sci USA. 2014;111:3757–3762. - PMC - PubMed
    1. Kinkel LL, Schlatter DC, Xiao K, Baines AD. Isme J. 2014;8:249–256. - PMC - PubMed
    2. Cordero OX, Wildschutte H, Kirkup B, Proehl S, Ngo L, Hussain F, Le Roux F, Mincer T, Polz MF. Science. 2012;337:1228–1231. - PubMed
    3. Czaran TL, Hoekstra RF, Pagie L. Proc Natl Acad Sci USA. 2002;99:786–790. - PMC - PubMed
    4. Weber MF, Poxleitner G, Hebisch E, Frey E, Opitz M. J R Soc Interface. 2014;11:20140172. - PMC - PubMed
    5. Abrudan MI, Smakman F, Grimbergen AJ, Westhoff S, Miller EL, van Wezel GP, Rozen DE. Proc Natl Acad Sci USA. 2015;112:11054–11059. - PMC - PubMed
    1. Gibson MK, Forsberg KJ, Dantas G. Isme J. 2015;9:207–216. - PMC - PubMed
    2. Pehrsson EC, Forsberg KJ, Gibson MK, Ahmadi S, Dantas G. Front Microbiol. 2013;4:145. - PMC - PubMed
    1. Blair JMA, Webber MA, Baylay AJ, Ogbolu DO, Piddock LJV. Nat Rev Microbiol. 2015;13:42–51. - PubMed
    1. Du L, Robles AJ, King JB, Powell DR, Miller AN, Mooberry SL, Cichewicz RH. Angew Chem Int Edit. 2014;53:804–809. - PMC - PubMed

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