title: Combinatorial profiling of chromatin binding modules reveals multisite discrimination.
abstract: Specific interactions between post-translational modifications (PTMs) and chromatin-binding proteins are central to the idea of a 'histone code'. Here, we used a 5,000-member, PTM-randomized, combinatorial peptide library based on the N terminus of histone H3 to interrogate the multisite specificity of six chromatin binding modules, which read the methylation status of Lys4. We found that Thr3 phosphorylation, Arg2 methylation and Thr6 phosphorylation are critical additional PTMs that modulate the ability to recognize and bind histone H3. Notably, phosphorylation of Thr6 yielded the most varied effect on protein binding, suggesting an important regulatory mechanism for readers of the H3 tail. Mass spectrometry and antibody-based evidence indicate that this previously uncharacterized modification exists on native H3, and NMR analysis of ING2 revealed the structural basis for discrimination. These investigations reveal a continuum of binding affinities in which multisite PTM recognition involves both switch- and rheostat-like properties, yielding graded effects that depend on the inherent 'reader' specificity.
authors.affiliation: [1] Department of Chemistry, University of Wisconsin, Madison, Wisconsin, USA. [2] These authors contributed equally to this work.
authors.forename: Adam L
authors.initials: AL
authors.lastname: Garske
authors.forename: Samuel S
authors.initials: SS
authors.lastname: Oliver
authors.forename: Elise K
authors.initials: EK
authors.lastname: Wagner
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Musselman
authors.forename: Gary
authors.initials: G
authors.lastname: LeRoy
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Garcia
authors.forename: Tatiana G
authors.initials: TG
authors.lastname: Kutateladze
authors.forename: John M
authors.initials: JM
authors.lastname: Denu
mesh_terms: D001665:Binding Sites; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006657:Histones / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008745:Methylation; D019151:Peptide Library; D011499:Protein Processing, Post-Translational
chemical_list: D002843:Chromatin; D006657:Histones; D019151:Peptide Library