A sequence-specific transcription activator motif and powerful synthetic variants that bind Mediator using a fuzzy protein interface

Proc Natl Acad Sci U S A. 2014 Aug 26;111(34):E3506-13. doi: 10.1073/pnas.1412088111. Epub 2014 Aug 13.

Abstract

Although many transcription activators contact the same set of coactivator complexes, the mechanism and specificity of these interactions have been unclear. For example, do intrinsically disordered transcription activation domains (ADs) use sequence-specific motifs, or do ADs of seemingly different sequence have common properties that encode activation function? We find that the central activation domain (cAD) of the yeast activator Gcn4 functions through a short, conserved sequence-specific motif. Optimizing the residues surrounding this short motif by inserting additional hydrophobic residues creates very powerful ADs that bind the Mediator subunit Gal11/Med15 with high affinity via a "fuzzy" protein interface. In contrast to Gcn4, the activity of these synthetic ADs is not strongly dependent on any one residue of the AD, and this redundancy is similar to that of some natural ADs in which few if any sequence-specific residues have been identified. The additional hydrophobic residues in the synthetic ADs likely allow multiple faces of the AD helix to interact with the Gal11 activator-binding domain, effectively forming a fuzzier interface than that of the wild-type cAD.

Keywords: Mediator complex; protein NMR.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Basic-Leucine Zipper Transcription Factors / chemistry*
  • Basic-Leucine Zipper Transcription Factors / genetics
  • Basic-Leucine Zipper Transcription Factors / metabolism*
  • Hydrophobic and Hydrophilic Interactions
  • Kinetics
  • Mediator Complex / chemistry*
  • Mediator Complex / genetics
  • Mediator Complex / metabolism*
  • Models, Molecular
  • Molecular Sequence Data
  • Multiprotein Complexes / chemistry
  • Multiprotein Complexes / metabolism
  • Mutagenesis, Site-Directed
  • Nuclear Magnetic Resonance, Biomolecular
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Transcriptional Activation

Substances

  • Basic-Leucine Zipper Transcription Factors
  • GAL11 protein, S cerevisiae
  • GCN4 protein, S cerevisiae
  • Mediator Complex
  • Multiprotein Complexes
  • Recombinant Proteins
  • Saccharomyces cerevisiae Proteins