The Elongator subunit Elp3 contains a Fe4S4 cluster and binds S-adenosylmethionine
Article first published online: 30 NOV 2005
Volume 59, Issue 3, pages 795–806, February 2006
How to Cite
Paraskevopoulou, C., Fairhurst, S. A., Lowe, D. J., Brick, P. and Onesti, S. (2006), The Elongator subunit Elp3 contains a Fe4S4 cluster and binds S-adenosylmethionine. Molecular Microbiology, 59: 795–806. doi: 10.1111/j.1365-2958.2005.04989.x
- Issue published online: 12 DEC 2005
- Article first published online: 30 NOV 2005
- Accepted 2 November, 2005.
The Elp3 subunit of the Elongator complex is highly conserved from archaea to humans and contains a well-characterized C-terminal histone acetyltransferase (HAT) domain. The central region of Elp3 shares significant sequence homology to the Radical SAM superfamily. Members of this large family of bacterial proteins contain a FeS cluster and use S-adenosylmethionine (SAM) to catalyse a variety of radical reactions. To biochemically characterize this domain we have expressed and purified the corresponding fragment of the Methanocaldococcus jannaschii Elp3 protein. The presence of a Fe4S4 cluster has been confirmed by UV-visible spectroscopy and electron paramagnetic resonance (EPR) spectroscopy and the Fe content determined by both a colorimetric assay and atomic absorption spectroscopy. The cysteine residues involved in cluster formation have been identified by site-directed mutagenesis. The protein binds SAM and the binding alters the EPR spectrum of the FeS cluster. Our results provide biochemical support to the hypothesis that Elp3 does indeed contain the Fe4S4 cluster which characterizes the Radical SAM superfamily and binds SAM, suggesting that Elp3, in addition to its HAT activity, has a second as yet uncharacterized catalytic function. We also present preliminary data to show that the protein cleaves SAM.