PMID: 22334692

Authors:

Culurgioni S, Munoz IG, Moreno A, Palacios A, Villate M, Palmero I, Montoya G, Blanco FJ

Title:

The crystal structure of the inhibitor of growth 4 (ING4) dimerization domain reveals the functional organization of the ING family of chromatin binding proteins.

Journal:

J Biol Chem. 2012 Feb 9.

Abstract:

The protein ING4 binds to histone H3 trimethylated at Lys4 (H3K4me3) through its C-terminal PlantHomeoDomain (PHD), thus recruiting the HBO1 histone acetyltransferase complex to target promoters. The structure of the PHD finger bound to an H3K4me3 peptide has been described, as well as the disorder and flexibility in the ING4 central region. We report the crystal structure of the ING4 N-terminal domain, which shows an antiparallel coiled-coil homodimer with each protomer folded into a helix-loop-helix structure. This arrangement suggests that ING4 can bind simultaneously two histone tails, on the same or different nucleosomes. Dimerization has a direct impact on ING4 tumor suppressor activity since monomeric mutants lose the ability of inducing apoptosis after genotoxic stress. Homology modeling based on the ING4 structure suggests that other ING dimers may also exist.