RT Journal Article
SR Electronic
T1 Large-scale in-cell photocrosslinking at single residue resolution reveals the molecular basis for glucocorticoid receptor regulation by immunophilins
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2023.01.16.524346
DO 10.1101/2023.01.16.524346
A1 Asat Baischew
A1 Sarah Engel
A1 Thomas M. Geiger
A1 Felix Hausch
YR 2023
UL http://biorxiv.org/content/early/2023/01/19/2023.01.16.524346.abstract
AB The large immunophilins FKBP51 and FKBP52 play key roles in the Hsp90-mediated maturation of steroid hormone receptors, which is crucial for stress-related disorders and correct sexual embryonic development, respectively 1–3. A prominent regulatory target is the glucocorticoid receptor (GR), whose activation is repressed by FKBP51 4,5 and facilitated by FKBP52 6,7. Despite their vital roles, the molecular modes of action of FKBP51 and FKBP52 are poorly understood since the transient key states of FKBP-mediated GR-regulation have remained experimentally elusive. Here we present the architecture and functional annotation of FKBP51-, FKBP52- and p23-containing Hsp90-apoGR preactivation complexes, trapped by systematic incorporation of photoreactive amino acids 8,9 inside human cells. The identified crosslinking sites depended on a functional Hsp90 chaperone cycle, were disrupted by GR activation, and clustered in characteristic patterns, defining the relative orientation and contact surfaces within the FKBP/p23-apoGR complexes. Strikingly, GR binding to the FKBPFK1 but not the FKBPFK2 domains were modulated by FKBP ligands, explaining the lack of FKBP51-mediated GR derepression by certain classes of FKBP ligands. These findings show how FKBP51 and FKBP52 differentially interact with the apoGR ligand binding domain, they explain the differentiated pharmacology of FKBP51 ligands, and provide a structural basis for the development of FKBP ligands with higher efficacy.Competing Interest StatementThe authors have declared no competing interest.