The asymmetric binding of PGC-1α to the ERRα and ERRγ nuclear receptor homodimers involves a similar recognition mechanism
Maria Takacs, Maxim V. Petoukhov, R. Andrew Atkinson, Pierre Roblin, François-Xavier Ogi, Borries Demeler, Noelle Potier, Yassmine Chebaro, Annick Dejaegere, Dmitri I. Svergun, Dino Moras, Isabelle M. L. Billas
2013 vol: 8 issue: 7 pp: e67810 doi: 10.1371/journal.pone.0067810
PGC-1α is a crucial regulator of cellular metabolism and energy homeostasis that functionally acts together with the estrogen-related receptors (ERRα and ERRγ) in the regulation of mitochondrial and metabolic gene networks. Dimerization of the ERRs is a pre-requisite for interactions with PGC-1α and other coactivators, eventually leading to transactivation. It was suggested recently (Devarakonda et al) that PGC-1α binds in a strikingly different manner to ERRγ ligand-binding domains (LBDs) compared to its mode of binding to ERRα and other nuclear receptors (NRs), where it interacts directly with the two ERRγ homodimer subunits.
Here, we show that PGC-1α receptor interacting domain (RID) binds in an almost identical manner to ERRα and ERRγ homodimers. Microscale thermophoresis demonstrated that the interactions between PGC-1α RID and ERR LBDs involve a single receptor subunit through high-affinity, ERR-specific L3 and low-affinity L2 interactions. NMR studies further defined the limits of PGC-1α RID that interacts with ERRs. Consistent with these findings, the solution structures of PGC-1α/ERRα LBDs and PGC-1α/ERRγ LBDs complexes share an identical architecture with an asymmetric binding of PGC-1α to homodimeric ERR.
These studies provide the molecular determinants for the specificity of interactions between PGC-1α and the ERRs, whereby negative cooperativity prevails in the binding of the coactivators to these receptors. Our work indicates that allosteric regulation may be a general mechanism controlling the binding of the coactivators to homodimers.
Topics: Small-angle scattering, Crystal structure, Dimers (Chemical physics), Sequence motif analysis, Biophysics, Molecular dynamics, Allosteric regulation, Protein structure prediction, Monolith – MicroScale Thermophoresis, MST, Proteins, Publications