title: Estrogen receptor α/β-cofactor motif interactions; interplay of tyrosine 537/488 phosphorylation and LXXLL motifs.
abstract: The Estrogen Receptors ERα and ERβ bind cofactor proteins via short LXXLL motifs. The exact regulation and selectivity of these interactions remains an open question and the role of post-translational modifications (PTMs) is virtually unexplored. Here, we designed an X(7)-LXXLL-X(7) T7 phage display library and screened this against four ER protein constructs: the 'naked' ERα and ERβ Ligand Binding Domains (LBDs) and the tyrosine phosphorylated ERα (pY537) and ERβ (pY488) LBDs. The site-selective tyrosine phosphorylated protein constructs were obtained via a protein semi-synthesis approach. Phage display screening yielded preferential sets of peptides. LXXLL peptides with a low pI/acidic C-terminus prefer binding to the naked ERβ over the phosphorylated ERβ analogue and ERα constructs. Peptides with a high pI/basic C-terminus show the opposite behaviour. These findings not only show regulation of the ERβ-cofactor interaction via tyrosine phosphorylation, but also suggest that ERβ and its tyrosine 488 phosphorylation play crucial roles in modulating interactions of coactivators to ERα since the natural Steroid Receptor Coactivators (SRCs) feature LXXLL motifs with acidic C-termini, while the repressor protein RIP140 features LXXLL motifs with basic C-termini. This insight provides explanation for ER transcriptional activity and can lead to more focussed targeting of the ER-coactivator interaction.
authors.affiliation: Laboratory of Chemical Biology, Department of Biomedical Engineering, Technische Universiteit Eindhoven, Den Dolech 2, Eindhoven, The Netherlands.
authors.forename: Hoang D
authors.initials: HD
authors.lastname: Nguyen
authors.forename: Trang T P
authors.initials: TT
authors.lastname: Phan
authors.forename: Maelle
authors.initials: M
authors.lastname: Carraz
authors.forename: Luc
authors.initials: L
authors.lastname: Brunsveld
mesh_terms: D000595:Amino Acid Sequence; D017123:Bacteriophage T7 / Q000235:genetics; D061505:Cell Surface Display Techniques; D047628:Estrogen Receptor alpha / Q000737:chemistry* / Q000378:metabolism*; D047629:Estrogen Receptor beta / Q000737:chemistry* / Q000378:metabolism*; D019151:Peptide Library; D010766:Phosphorylation; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D020539:Sequence Analysis, Protein; D014158:Transcription, Genetic
chemical_list: D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D019151:Peptide Library