Extension of the Binding Motif of the Sin3 Interacting Domain of the Mad Family Proteins

• Published in: Biochemistry (Easton) Vol. 43; no. 1; pp. 46 - 54
• Main Authors: van Ingen, Hugo, Lasonder, Edwin, Jansen, Jacobus F. A, Kaan, Anita M, Spronk, Christian A. E. M, Stunnenberg, Henk G, Vuister, Geerten W
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 13.01.2004
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Animals; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Caenorhabditis elegans Proteins - chemistry; Conserved Sequence; Crystallography, X-Ray; DNA-Binding Proteins - chemistry; Fungal Proteins - chemistry; Histone Deacetylases; Humans; Membrane Proteins - chemistry; Molecular Sequence Data; Multigene Family; Nuclear Magnetic Resonance, Biomolecular; Protein Binding; Protein Structure, Tertiary; Repressor Proteins; Saccharomyces cerevisiae Proteins; Sequence Alignment; Sequence Homology, Amino Acid; Solutions; Surface Plasmon Resonance; Thermodynamics; Transcription Factors - chemistry
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi0355645

Sin3 forms the scaffold for a multiprotein corepressor complex that silences transcription via the action of histone deacetylases. Sin3 is recruited to the DNA by several DNA binding repressors, such as the helix−loop−helix proteins of the Mad family. Here, we elaborate on the Mad−Sin3 interaction based on a binding study, solution structure, and dynamics of the PAH2 domain of mSin3 in complex to an extended Sin3 interacting domain (SID) of 24 residues of Mad1. We show that SID residues Met7 and Glu23, outside the previously defined minimal binding motif, mediate additional hydrophobic and electrostatic interactions with PAH2. On the basis of these results we propose an extended consensus sequence describing the PAH2−SID interaction specifically for the Mad family, showing that residues outside the hydrophobic core of the SID interact with PAH2 and modulate binding affinity to appropriate levels.