Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5371984 | Biophysical Chemistry | 2008 | 6 Pages |
Stopped-flow fluorescence anisotropy was used to determine the kinetic parameters that define acetylation-dependent bromodomain-histone interactions. Bromodomains are acetyllysine binding motifs found in many chromatin associated proteins. Individual bromodomains were derived from the polybromo-1 protein, which is a subunit of the PBAF chromatin-remodeling complex that has six tandem bromodomains in the amino-terminal region. The average kon and koff values for the formation of high-affinity complexes are 275 Mâ 1 sâ 1 and 0.41 Ã 10â 3 sâ 1, respectively. The average kon and koff values for the formation of low-affinity complexes are 119 Mâ 1 sâ 1 and 1.42 Ã 10â 3 sâ 1, respectively. Analysis of the on- and off-rates yields acetylation site-dependent equilibrium dissociation constants averaging 1.4 and 12.9 μM for high- and low-affinity complexes, respectively. This work represents the first examination of kinetic mechanisms of acetylation-dependent bromodomain-histone interactions.