A ligand-mediated hydrogen bond network required for the activation of the mineralocorticoid receptor.
Ligand binding is the first step in hormone regulation of mineralocorticoid receptor (MR) activity. Here, we report multiple crystal structures of MR (NR3C2) bound to both agonist and antagonists. These structures combined with mutagenesis studies reveal that maximal receptor activation involves an intricate ligand-mediated hydrogen bond network with Asn770 which serves dual roles: stabilization of the loop preceding the C-terminal activation function-2 helix and direct contact with the hormone ligand. In addition, most activating ligands hydrogen bond to Thr945 on helix 10. Structural characterization of the naturally occurring S810L mutant explains how stabilization of a helix 3/helix 5 interaction can circumvent the requirement for this hydrogen bond network. Taken together, these results explain the potency of MR activation by aldosterone, the weak activation induced by progesterone and the antihypertensive agent spironolactone, and the binding selectivity of cortisol over cortisone.
Bledsoe
Randy K
RK
Department of Gene Expression and Protein Biochemistry, GlaxoSmithKline, Research Triangle Park, North Carolina 27709, USA. randy.k.bledsoe@gsk.com
Madauss
Kevin P
KP
Holt
Jason A
JA
Apolito
Christopher J
CJ
Lambert
Millard H
MH
Pearce
Kenneth H
KH
Stanley
Thomas B
TB
Stewart
Eugene L
EL
Trump
Ryan P
RP
Willson
Timothy M
TM
Williams
Shawn P
SP
D018360:Crystallography, X-Ray; D006801:Humans; D006860:Hydrogen Bonding; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009154:Mutation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D018161:Receptors, Mineralocorticoid / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013256:Steroids / Q000737:chemistry / Q000378:metabolism; D015533:Transcriptional Activation
D008024:Ligands; D018161:Receptors, Mineralocorticoid; D013256:Steroids