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The radical SAM enzyme AlbA catalyzes thioether bond formation in subtilosin A

Nature Chemical Biology volume 8, pages 350–357 (2012)Cite this article

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An Erratum to this article was published on 18 July 2012

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Abstract

Subtilosin A is a 35-residue, ribosomally synthesized bacteriocin encoded by the sbo-alb operon of Bacillus subtilis. It is composed of a head-to-tail circular peptide backbone that is additionally restrained by three unusual thioether bonds between three cysteines and the α-carbon of one threonine and two phenylalanines, respectively. In this study, we demonstrate that these bonds are synthesized by the radical S-adenosylmethionine enzyme AlbA, which is encoded by the sbo-alb operon and comprises two [4Fe-4S] clusters. One [4Fe-4S] cluster is coordinated by the prototypical CXXXCXXC motif and is responsible for the observed S-adenosylmethionine cleavage reaction, whereas the second [4Fe-4S] cluster is required for the generation of all three thioether linkages. On the basis of the obtained results, we propose a new radical mechanism for thioether bond formation. In addition, we show that AlbA-directed substrate transformation is leader-peptide dependent, suggesting that thioether bond formation is the first step during subtilosin A maturation.

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Figure 1: Characterization of AlbA as a radical SAM enzyme.
Figure 2: Precursor-peptide modification assays and alignment.
Figure 3: Postulated biosynthesis of subtilosin A.
Figure 4: Proposed mechanism for thioether bond formation.

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Change history

  • 16 April 2012

    In the version of this article initially published, S-adenosyl methionine was drawn with a radical instead of a cation in Figure 4. The error has been corrected in the HTML and PDF versions of the article.

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Acknowledgements

We would like to thank N. Fritzler and J. Bamberger for practical realization of the HPLC-HRMS measurements. In addition, we would like to thank the whole Marahiel group for fruitful discussions. Furthermore, we gratefully acknowledge financial support from the Deutsche Forschungsgemeinschaft and from the LOEWE Center for Synthetic Microbiology.

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  1. Michael J Gattner

    Present address: Present address: Fakultät für Chemie und Pharmazie, Ludwig-Maximilians-Universität München, München, Germany.,

Authors and Affiliations

  1. Department of Chemistry–Biochemistry, Philipps-Universität Marburg, Marburg, Germany

    Leif Flühe, Thomas A Knappe, Michael J Gattner, Antje Schäfer, Olaf Burghaus, Uwe Linne & Mohamed A Marahiel

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Contributions

T.A.K. and M.A.M. initiated the project. M.J.G., L.F. and T.A.K. conceived the experiments. M.J.G. performed preliminary experiments for the characterization of AlbA. L.F. performed most experiments. M.J.G. and L.F. prepared the figures. O.B. carried out the EPR measurements. U.L. designed the HPLC-MS gradients and carried out the measurements. A.S. cloned, expressed and purified AlbA. L.F. and T.A.K. analyzed and interpreted the obtained data. L.F., T.A.K. and M.A.M. coordinated the project and wrote the manuscript.

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Correspondence to Mohamed A Marahiel.

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Flühe, L., Knappe, T., Gattner, M. et al. The radical SAM enzyme AlbA catalyzes thioether bond formation in subtilosin A. Nat Chem Biol 8, 350–357 (2012). https://doi.org/10.1038/nchembio.798

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