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Article Dans Une Revue FEBS Journal Année : 2005

Mechanism of binding of serum response factor to serum response element.

Résumé

Serum response factor (SRF) is a MADS transcription factor that binds to the CArG box sequence of the serum response element (SRE). Through its binding to CArG sequences, SRF activates several muscle-specific genes as well as genes that respond to mitogens. The thermodynamic parameters of the interaction of core-SRF (the 124-245 fragment of serum response factor) with specific oligonucleotides from c-fos and desmin promoters, were determined by spectroscopy. The rotational correlation time of core-SRF labeled with bis-ANS showed that the protein is monomeric at low concentration (10(-7) m). The titration curves for the fluorescence anisotropy of fluorescein-labeled oligonucleotide revealed that under equilibrium conditions, the core-SRF monomers were bound sequentially to SRE at very low concentration (10(-9) m). Curve-fitting data showed also major differences between the wild-type sequence and the oligonucleotide sequences mutated within the CArG box. The fluorescence of the core-SRF tyrosines was quenched by the SRE oligonucleotide. This quenching indicated that under stoichiometric conditions, core-SRF was bound as a dimer to the wild-type oligonucleotide, and as a monomer or a tetramer to the mutant oligonucleotides. Far-UV CD spectra indicated that the flexibility of core-SRF changed profoundly upon its binding to its specific target SRE. Lastly, the rotational correlation time of fluorescein-labeled SRE revealed that formation of the specific complex was accompanied by a change in the SRE internal dynamics. These results indicated that the flexibility of the two partners is crucial for the DNA-protein interaction.

Dates et versions

hal-00258370 , version 1 (21-02-2008)

Identifiants

Citer

Alexis Huet, Ara Parlakian, Marie-Claire Arnaud, Jean-Marie Glandières, Pierre Valat, et al.. Mechanism of binding of serum response factor to serum response element.. FEBS Journal, 2005, 272 (12), pp.3105-19. ⟨10.1111/j.1742-4658.2005.04724.x⟩. ⟨hal-00258370⟩
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