Ligand-induced architecture of the leptin receptor signaling complex.
Despite the crucial impact of leptin signaling on metabolism and body weight, little is known about the structure of the liganded leptin receptor (LEP-R) complex. Here, we applied single-particle electron microscopy (EM) to characterize the architecture of the extracellular region of LEP-R alone and in complex with leptin. We show that unliganded LEP-R displays significant flexibility in a hinge region within the cytokine homology region 2 (CHR2) that is connected to rigid membrane-proximal FnIII domains. Leptin binds to CHR2 in order to restrict the flexible hinge and the disposition of the FnIII "legs." Through a separate interaction, leptin engages the Ig-like domain of a second liganded LEP-R, resulting in the formation of a quaternary signaling complex. We propose that the membrane proximal domain rigidification in the context of a liganded cytokine receptor dimer is a key mechanism for the transactivation of Janus kinases (Jaks) bound at the intracellular receptor region.
Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA.
Liliya V
LV
Mancour
Hikmat N
HN
Daghestani
Somnath
S
Dutta
Gerwin H
GH
Westfield
Justin
J
Schilling
Austin N
AN
Oleskie
Jeffrey F
JF
Herbstman
Steven Z
SZ
Chou
Georgios
G
Skiniotis
D006801:Humans; D020738:Leptin / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D008024:Ligands; D008854:Microscopy, Electron; D008958:Models, Molecular; D011487:Protein Conformation / Q000187:drug effects; D054411:Receptors, Leptin / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D015398:Signal Transduction / Q000187:drug effects*
D020738:Leptin; D008024:Ligands; D054411:Receptors, Leptin