4qjr
From Proteopedia
Crystal structure of human nuclear receptor sf-1 (nr5a1) bound to its hormone pip3 at 2.4 a resolution
Structural highlights
DiseaseSTF1_HUMAN Defects in NR5A1 are a cause of 46,XY sex reversal type 3 (SRXY3) [MIM:612965. A condition characterized by male-to-female sex reversal in the presence of a normal 46,XY karyotype.[1] [2] [3] [4] Defects in NR5A1 are a cause of adrenocortical insufficiency without ovarian defect (ACIWOD) [MIM:184757. ACIWOD is characterized by severe 'slackness' muscular hypotonia. There is decreased sodium, increased potassium and elevated ACTH.[5] Defects in NR5A1 are the cause of premature ovarian failure type 7 (POF7) [MIM:612964. An ovarian disorder defined as the cessation of ovarian function under the age of 40 years. It is characterized by oligomenorrhea or amenorrhea, in the presence of elevated levels of serum gonadotropins and low estradiol.[6] Defects in NR5A1 are the cause of spermatogenic failure type 8 (SPGF8) [MIM:613957. SPGF8 is an infertility disorder characterized by spermatogenesis failure and severe oligozoospermia.[7] FunctionSTF1_HUMAN Transcriptional activator. Seems to be essential for sexual differentiation and formation of the primary steroidogenic tissues. Binds to the Ad4 site found in the promoter region of steroidogenic P450 genes such as CYP11A, CYP11B and CYP21B. Also regulates the AMH/Muellerian inhibiting substance gene as well as the AHCH and STAR genes. 5'-YCAAGGYC-3' and 5'-RRAGGTCA-3' are the consensus sequences for the recognition by NR5A1. The SFPQ-NONO-NR5A1 complex binds to the CYP17 promoter and regulates basal and cAMP-dependent transcriptional avtivity. Binds phosphatidylcholine (By similarity). Binds phospholipids with a phosphatidylinositol (PI) headgroup, in particular PI(3,4)P2 and PI(3,4,5)P3. Activated by the phosphorylation of NR5A1 by HIPK3 leading to increased steroidogenic gene expression upon cAMP signaling pathway stimulation.[8] Publication Abstract from PubMedThe signaling phosphatidylinositol lipids PI(4,5)P2 (PIP2) and PI(3,4,5)P3 (PIP3) bind nuclear receptor 5A family (NR5As), but their regulatory mechanisms remain unknown. Here, the crystal structures of human NR5A1 (steroidogenic factor-1, SF-1) ligand binding domain (LBD) bound to PIP2 and PIP3 show the lipid hydrophobic tails sequestered in the hormone pocket, as predicted. However, unlike classic nuclear receptor hormones, the phosphoinositide head groups are fully solvent-exposed and complete the LBD fold by organizing the receptor architecture at the hormone pocket entrance. The highest affinity phosphoinositide ligand PIP3 stabilizes the coactivator binding groove and increases coactivator peptide recruitment. This receptor-ligand topology defines a previously unidentified regulatory protein-lipid surface on SF-1 with the phosphoinositide head group at its nexus and poised to interact with other proteins. This surface on SF-1 coincides with the predicted binding site of the corepressor DAX-1 (dosage-sensitive sex reversal, adrenal hypoplasia critical region on chromosome X), and importantly harbors missense mutations associated with human endocrine disorders. Our data provide the structural basis for this poorly understood cluster of human SF-1 mutations and demonstrates how signaling phosphoinositides function as regulatory ligands for NR5As. The signaling phospholipid PIP3 creates a new interaction surface on the nuclear receptor SF-1.,Blind RD, Sablin EP, Kuchenbecker KM, Chiu HJ, Deacon AM, Das D, Fletterick RJ, Ingraham HA Proc Natl Acad Sci U S A. 2014 Oct 21;111(42):15054-9. doi:, 10.1073/pnas.1416740111. Epub 2014 Oct 6. PMID:25288771[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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