Article | Published:

Radical-mediated enzymatic carbon chain fragmentation-recombination

Nature Chemical Biology volume 7, pages 154160 (2011) | Download Citation

Abstract

The radical S-adenosylmethionine (S-AdoMet) superfamily contains thousands of proteins that catalyze highly diverse conversions, most of which are poorly understood, owing to a lack of information regarding chemical products and radical-dependent transformations. We here report that NosL, involved in forming the indole side ring of the thiopeptide nosiheptide (NOS), is a radical S-AdoMet 3-methyl-2-indolic acid (MIA) synthase. NosL catalyzed an unprecedented carbon chain reconstitution of L-tryptophan to give MIA, showing removal of the Cα-N unit and shift of the carboxylate to the indole ring. Dissection of the enzymatic process upon the identification of products and a putative glycyl intermediate uncovered a radical-mediated, unusual fragmentation-recombination reaction. This finding unveiled a key step in radical S-AdoMet enzyme–catalyzed structural rearrangements during complex biotransformations. Additionally, NosL tolerated fluorinated L-tryptophan as the substrate, allowing for production of a regiospecifically halogenated thiopeptide that has not been found among the more than 80 members of the naturally occurring thiopeptide family.

  • Compound C10H9NO2

    3-Methyl-2-indolic acid

  • Compound C10H13N5O3

    5'-Deoxyadenosine

  • Compound C9H9N

    3-Methylindole

  • Compound C8H6N4O6

    2-(2,4-Dinitrophenyl) hydrazonoacetate

  • Compound C7H6N4O4

    1-(2,4-Dinitrophenyl)-2-methylene hydrazine

  • Compound C14H16N2O4S

    Dansylglycine

  • Compound C17H22N2O4S2

    Dansyl-L-methionine

  • Compound C10H8FNO2

    5-Fluoro-3-methyl-2-indolic acid

  • Compound C10H8FNO2

    6-Fluoro-3-methyl-2-indolic acid

  • Compound C51H42FN13O12S6

    5'-Fluoronosiheptide

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Acknowledgements

We thank H.G. Floss (University of Washington) for providing S. actuosus ATCC25421 and for his pioneering work on NOS biosynthesis and Y. Zhang and W. Tong, (High Magnetic Field Laboratory, Chinese Academy of Sciences) for assistance with EPR analysis. This work was supported in part by grants from US National Institutes of Health (CA094426 to B.S.), Chinese National Natural Science Foundation (20832009, 30525001, 90713012 and 20921091), Chinese Ministry of Science and Technology (2009ZX09501-008), Chinese National Basic Research Program (“973 program,” 2010CB833200), Chinese Academy of Sciences (KJCX2-YW-H08 and KSCX2-YW-G-06) and Science and Technology Commission of Shanghai Municipality (09QH1402700) of China (all to W.L).

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Affiliations

  1. State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.

    • Qi Zhang
    • , Dandan Chen
    • , Yi Yu
    • , Lian Duan
    •  & Wen Liu
  2. State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.

    • Yuxue Li
  3. Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA.

    • Ben Shen

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Contributions

Q.Z., D.C., Y.Y. and L.D. carried out the experiments; Y.L. performed the theoretical calculations; Q.Z., B.S. and W.L. analyzed the data and wrote the paper; and W.L. designed the research. All authors discussed results and approved the final manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Wen Liu.

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DOI

https://doi.org/10.1038/nchembio.512

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