PMID: 23651431

Authors:

Bruschweiler S, Konrat R, Tollinger M

Title:

Allosteric Communication in the KIX Domain Proceeds through Dynamic Repacking of the Hydrophobic Core.

Journal:

ACS Chem Biol. 2013 May 20.

Abstract:

The KIX domain of the transcriptional coactivator CREB binding protein (CBP) co-operatively mediates interactions between transcription factors. Binding of the transcription factor mixed-lineage leukemia (MLL) induces the formation of a low-populated conformer of KIX that resembles the conformation of the KIX domain in the presence of a second transcription factor molecule. NMR spin relaxation studies have previously shown that allosteric coupling proceeds through a network of hydrophobic core residues that bridge the two binding sites. Here we describe high-resolution NMR solution structures of the binary complex of KIX with MLL and the ternary complex of KIX formed with MLL and phosphorylated kinase inducible domain of CREB (pKID) as a second ligand. We show that binding of pKID to the binary complex of KIX with MLL is accompanied by a defined repacking of the allosteric network in the hydrophobic core of the protein. Rotamer populations derived from methyl group 13C chemical shifts reveal a dynamic contribution to the repacking process that is not captured by the structural coordinates and exemplify the dynamic nature of allosteric communication in the KIX domain.