Structural adaptability in the ligand-binding pocket of the ecdysone hormone receptor.
The ecdysteroid hormones coordinate the major stages of insect development, notably moulting and metamorphosis, by binding to the ecdysone receptor (EcR); a ligand-inducible nuclear transcription factor. To bind either ligand or DNA, EcR must form a heterodimer with ultraspiracle (USP), the homologue of retinoid-X receptor. Here we report the crystal structures of the ligand-binding domains of the moth Heliothis virescens EcR-USP heterodimer in complex with the ecdysteroid ponasterone A and with a non-steroidal, lepidopteran-specific agonist BYI06830 used in agrochemical pest control. The two structures of EcR-USP emphasize the universality of heterodimerization as a general mechanism common to both vertebrates and invertebrates. Comparison of the EcR structures in complex with steroidal and non-steroidal ligands reveals radically different and only partially overlapping ligand-binding pockets that could not be predicted by molecular modelling and docking studies. These findings offer new perspectives for the design of insect-specific, environmentally safe insecticides. The concept of a ligand-dependent binding pocket in EcR provides an insight into the moulding of nuclear receptors to their ligand, and has potential applications for human nuclear receptors.
Département de Biologie et de Génomique Structurales, IGBMC, CNRS/INSERM/Université Louis Pasteur, Parc d'Innovation BP10142, 67404 Illkirch cedex, France.
Isabelle M L
IM
Billas
Thomas
T
Iwema
Jean-Marie
JM
Garnier
André
A
Mitschler
Natacha
N
Rochel
Dino
D
Moras
D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004146:Dioxanes / Q000737:chemistry / Q000378:metabolism*; D004441:Ecdysterone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D006834:Hydrazines / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D008958:Models, Molecular; D009036:Moths / Q000737:chemistry*; D011487:Protein Conformation; D011987:Receptors, Steroid / Q000737:chemistry* / Q000378:metabolism*
C479521:BYI 06830; D004146:Dioxanes; D006834:Hydrazines; D008024:Ligands; D011987:Receptors, Steroid; C055469:ecdysone receptor; D004441:Ecdysterone; C008999:ponasterone A