Structural studies of the interaction of S-adenosylmethionine with the [4Fe-4S] clusters in biotin synthase and pyruvate formate-lyase activating enzyme - PubMed (original) (raw)

Structural studies of the interaction of S-adenosylmethionine with the [4Fe-4S] clusters in biotin synthase and pyruvate formate-lyase activating enzyme

Michele M Cosper et al. Protein Sci. 2003 Jul.

Abstract

The diverse reactions catalyzed by the radical-SAM superfamily of enzymes are thought to proceed via a set of common mechanistic steps, key among which is the reductive cleavage of S-adenosyl-L-methionine (SAM) by a reduced [4Fe-4S] cluster to generate an intermediate deoxyadenosyl radical. A number of spectroscopic studies have provided evidence that SAM interacts directly with the [4Fe-4S] clusters in several of the radical-SAM enzymes; however, the molecular mechanism for the reductive cleavage has yet to be elucidated. Selenium X-ray absorption spectroscopy (Se-XAS) was used previously to provide evidence for a close interaction between the Se atom of selenomethionine (a cleavage product of Se-SAM) and an Fe atom of the [4Fe-4S] cluster of lysine-2,3-aminomutase (KAM). Here, we utilize the same approach to investigate the possibility of a similar interaction in pyruvate formate-lyase activating enzyme (PFL-AE) and biotin synthase (BioB), two additional members of the radical-SAM superfamily. The results show that the latter two enzymes do not exhibit the same Fe-Se interaction as was observed in KAM, indicating that the methionine product of reductive cleavage of SAM does not occupy a well-defined site close to the cluster in PFL-AE and BioB. These results are interpreted in terms of the differences among these enzymes in their use of SAM as either a cofactor or a substrate.

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Figures

Figure 1.

Figure 1.

Proposed mode of interaction of SAM with the [4Fe-4S] cluster of PFL-AE. The model is based on electron-nuclear double resonance and Mössbauer studies (Krebs et al. 2002; Walsby et al. 2002a,b).

Figure 2.

Figure 2.

Fourier transforms (over k = 2–12.5 Å−1) for (A) lysine 2,3-aminomutase incubated with SeMet, 5′deoxyadenosine, and didehydrolysine (solid line) and the calculated spectra for Se-C,Fe (Cosper et al. 2000); (B) PFL-AE [4Fe-4S]2+ incubated with SeMet and PFL (solid line) and the calculated spectra for Se-C2 (broken line; Fit 2, Table 1▶); and (C) BioB incubated with SeMet, d-biotin, and 5′deoxyadenosine (solid line) and the calculated spectra for Se-C2 (broken line; Fit 6, Table 1▶).

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References

    1. Baldet, P., Alban, C., and Douce, R. 1997. Biotin synthesis in higher plants: Purification and characterization of bioB gene product equivalent from Arabidopsis thaliana overexpressed in Escherichia coli and its subcellular localization in pea leaf cells. FEBS Lett. 419 206–210. - PubMed
    1. Beinert, H. 2000. Iron-sulfur proteins: Ancient structures, still full of surprises. J. Biol. Inorg. Chem. 5 2–15. - PubMed
    1. Beinert, H., Holm, R.H., and Münck, E. 1997. Iron-sulfur clusters: Nature’s modular, multipurpose structures. Science 277 653–659. - PubMed
    1. Broderick, J.B., Duderstadt, R.E., Fernandez, D.C., Wojtuszewski, K., Henshaw, T.F., and Johnson, M.K. 1997. Pyruvate formate-lyase activating enzyme is an iron-sulfur protein. J. Am. Chem. Soc. 119 7396–7397.
    1. Broderick, J.B., Henshaw, T.F., Cheek, J., Wojtuszewski, K., Smith, S.R., Trojan, M.R., McGhan, R.M., Kopf, A., Kibbey, M., and Broderick, W.E. 2000. Pyruvate formate-lyase-activating enzyme: Strictly anaerobic isolation yields active enzyme containing a [3Fe-4S]+ cluster. Biochem. Biophys. Res. Commun. 269 451–456. - PubMed

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