Allosteric conversation in the androgen receptor ligand-binding domain surfaces.
Androgen receptor (AR) is a major therapeutic target that plays pivotal roles in prostate cancer (PCa) and androgen insensitivity syndromes. We previously proposed that compounds recruited to ligand-binding domain (LBD) surfaces could regulate AR activity in hormone-refractory PCa and discovered several surface modulators of AR function. Surprisingly, the most effective compounds bound preferentially to a surface of unknown function [binding function 3 (BF-3)] instead of the coactivator-binding site [activation function 2 (AF-2)]. Different BF-3 mutations have been identified in PCa or androgen insensitivity syndrome patients, and they can strongly affect AR activity. Further, comparison of AR x-ray structures with and without bound ligands at BF-3 and AF-2 showed structural coupling between both pockets. Here, we combine experimental evidence and molecular dynamic simulations to investigate whether BF-3 mutations affect AR LBD function and dynamics possibly via allosteric conversation between surface sites. Our data indicate that AF-2 conformation is indeed closely coupled to BF-3 and provide mechanistic proof of their structural interconnection. BF-3 mutations may function as allosteric elicitors, probably shifting the AR LBD conformational ensemble toward conformations that alter AF-2 propensity to reorganize into subpockets that accommodate N-terminal domain and coactivator peptides. The induced conformation may result in either increased or decreased AR activity. Activating BF-3 mutations also favor the formation of another pocket (BF-4) in the vicinity of AF-2 and BF-3, which we also previously identified as a hot spot for a small compound. We discuss the possibility that BF-3 may be a protein-docking site that binds to the N-terminal domain and corepressors. AR surface sites are attractive pharmacological targets to develop allosteric modulators that might be alternative lead compounds for drug design.
Joint BSC-IRB Research Programme in Computational Biology, Life Sciences Department, Barcelona Supercomputing Center, 08034 Barcelona, Spain.
Solène
S
Grosdidier
Laia R
LR
Carbó
Víctor
V
Buzón
Greg
G
Brooke
Phuong
P
Nguyen
John D
JD
Baxter
Charlotte
C
Bevan
Paul
P
Webb
Eva
E
Estébanez-Perpiñá
Juan
J
Fernández-Recio
D013734:Androgen-Insensitivity Syndrome / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D045744:Cell Line, Tumor; D006367:HeLa Cells; D006801:Humans; D008024:Ligands; D008297:Male; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D009154:Mutation; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D017434:Protein Structure, Tertiary; D011944:Receptors, Androgen / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D008024:Ligands; D011944:Receptors, Androgen