The N-terminal methionine is a major determinant of the DNA binding specificity of MEF-2C

Meierhans, D. and Allemann, Rudolf Konrad ORCID: https://orcid.org/0000-0002-1323-8830 1998. The N-terminal methionine is a major determinant of the DNA binding specificity of MEF-2C. Journal of Biological Chemistry 273 (40) , pp. 26052-26060. 10.1074/jbc.273.40.26052

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Abstract

Members of the MEF-2 family of transcriptional regulators positively modulate the activity of basic helix-loop-helix proteins in both myogenic and neurogenic cell lineages. Previous work had shown that MEF-2C(2–117), a protein fragment comprising the dimerization and DNA-binding domains of MEF-2C but lacking the N-terminal methionine, bound to AT-rich DNA sequences with high affinity. MEF-2C(2–117) did not discriminate between different AT-rich sequences. We now report the in vitro DNA binding properties of a MEF-2C fragment containing the N-terminal methionine. Measurements of the apparent dissociation constants of the complexes of GG-MEF-2C(1–117) revealed that different AT-rich sequences are bound with different affinities; in particular MEF site containing DNA (CTATAAATAG) is bound preferentially to DNA containing a SRF site (CATAAATG). Strikingly, when the shorter AT run consisted of six alternating thymines and adenines, almost wild-type affinity was observed. Irrespective of the particular DNA sequence, all circular dichroism spectra of the DNA complexes of GG-MEF-2C(1–117) were superimposable and characterized by an identical maximal ellipticity at 269.5 nm, suggesting similar DNA conformations. Bending analysis by circular permutation assay revealed that on complex formation MEF-2C(2–117) induced cognate DNA to bend by 49°, while heterologous DNA remained unbent. In the presence of the N-terminal methionine, however, all DNA sequences were bent by 70°. The above results suggest an important function for the N-terminal methionine in properly orientating MEF-2C on the DNA.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry Cardiff Catalysis Institute (CCI)
Subjects:	Q Science > QD Chemistry
Publisher:	American Society for Biochemistry and Molecular Biology
ISSN:	0021-9258
Last Modified:	18 Oct 2022 13:19
URI:	https://orca.cardiff.ac.uk/id/eprint/13465

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