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Identification of polyproline II regions derived from the proline-rich nuclear receptor coactivators PNRC and PNRC2:

C Byrne1, E Miclet, I Broutin

  • 1Laboratoire des BioMolécules (LBM), CNRS - UMR 7203, Ecole Normale Supérieure / Université Pierre et Marie Curie 24, rue Lhomond, 75231, Paris Cedex 05, France; Fondation Pierre-Gilles de Gennes pour la Recherche, 29, rue d'Ulm, 75005, Paris, France.

Chirality
|August 9, 2013
PubMed

Insights

Nuclear receptor coactivators PNRC and PNRC2 utilize PxxP motifs to interact with estrogen receptor alpha (ERα). This study reveals a novel polyproline II (PPII) recognition site within ERα's AF-2 domain, crucial for transcriptional regulation.

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Biochemistry

Background:

  • Protein-protein interactions are vital for cellular signaling, differentiation, and proliferation, making them key therapeutic targets, especially in cancer.
  • Nuclear receptor coactivators PNRC and PNRC2 are known to interact with estrogen receptor alpha (ERα) via PxxP motifs.
  • Understanding the molecular basis of these interactions is crucial for developing targeted therapies.

Purpose of the Study:

  • To investigate the molecular features governing the interaction between PNRC/PNRC2 and ERα.
  • To explore the capacity of peptides derived from PNRC and PNRC2, containing PxxP motifs, to form polyproline II (PPII) domains.
  • To identify potential PPII recognition sites within ERα.

Main Methods:

  • Electronic Circular Dichroism (ECD) spectroscopy and Molecular Dynamics (MD) calculations were employed to study peptide structures.
  • 2D Nuclear Magnetic Resonance (NMR) spectroscopy was used for an in-depth structural analysis of a lead PPII peptide.
  • Binding assays were conducted to assess peptide interactions with Grb2 SH3 domains and a synthetic ERα peptide (ERα17p).

Main Results:

  • Most investigated peptides containing PxxP motifs did not bind to Grb2 SH3 domains, suggesting distinct binding modes for antagonists versus agonists.
  • These peptides demonstrated competitive binding against ERα17p, indicating a PPII recognition site within ERα's AF-2 domain.
  • The study confirmed the presence of PxxP-induced PPII sequences in PNRC and PNRC2, and a PPII recognition site in ERα's AF-2 region.

Conclusions:

  • This research provides the first structure-related interaction study of PNRC and PNRC2 with ERα.
  • It supports the existence of PxxP-induced PPII sequences in these nuclear receptor coactivators.
  • The findings confirm a PPII recognition site in the AF-2 domain of ERα, a critical region for transcriptional regulation.
Keywords:
NMRelectronic circular dichroismestrogen receptor αmolecular dynamicspolyproline IIproline-rich nuclear receptor coactivator PNRC

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