11 research outputs found
Structural Basis for alpha-Helix Mimicry and Inhibition of Protein-Protein Interactions with Oligourea Foldamers
Efficient optimization of a peptide lead into a drug candidate frequently needs further transformation to augment properties such as bioavailability. Among the different options, foldamers, which are sequence-based oligomers with precise folded conformation, have emerged as a promising technology. We introduce oligourea foldamers to reduce the peptide character of inhibitors of protein-protein interactions (PPI). However, the precise design of such mimics is currently limited by the lack of structural information on how these foldamers adapt to protein surfaces. We report a collection of X-ray structures of peptide-oligourea hybrids in complex with ubiquitin ligase MDM2 and vitamin D receptor and show how such hybrid oligomers can be designed to bind with high affinity to protein targets. This work should enable the generation of more effective foldamer-based disruptors of PPIs in the context of peptide lead optimization
Molecular determinants of MED1 interaction with the DNA bound VDRâRXR heterodimer
International audienceThe MED1 subunit of the Mediator complex is an essential coactivator of nuclear receptor-mediated transcriptional activation. While structural requirements for ligand-dependent binding of classical coactivator motifs of MED1 to numerous nuclear receptor ligand-binding domains have been fully elucidated, the recognition of the full-length or truncated coactivator by full nuclear receptor complexes remain unknown. Here we present structural details of the interaction between a large part of MED1 comprising its structured N-terminal and the flexible receptor-interacting domains and the mutual heterodimer of the vitamin D receptor (VDR) and the retinoid X receptor (RXR) bound to their cognate DNA response element. Using a combination of structural and biophysical methods we show that the ligand-dependent interaction between VDR and the second coactivator motif of MED1 is crucial for complex formation and we identify additional, previously unseen, interaction details. In particular, we identified RXR regions involved in the interaction with the structured N-terminal domain of MED1, as well as VDR regions outside the classical coactivator binding cleft affected by coactivator recruitment. These findings highlight important roles of each receptor within the heterodimer in selective recognition of MED1 and contribute to our understanding of the nuclear receptor-coregulator complexes
Structural Insights into the Molecular Mechanism of Vitamin D Receptor Activation by Lithocholic Acid Involving a New Mode of Ligand Recognition
The
vitamin D receptor (VDR), an endocrine nuclear receptor for
1α,25-dihydroxyvitamin D3, acts also as a bile acid sensor by
binding lithocholic acid (LCA). The crystal structure of the zebrafish
VDR ligand binding domain in complex with LCA and the SRC-2 coactivator
peptide reveals the binding of two LCA molecules by VDR. One LCA binds
to the canonical ligand-binding pocket, and the second one, which
is not fully buried, is anchored to a site located on the VDR surface.
Despite the low affinity of the alternative site, the binding of the
second molecule promotes stabilization of the active receptor conformation.
Biological activity assays, structural analysis, and molecular dynamics
simulations indicate that the recognition of two ligand molecules
is crucial for VDR agonism by LCA. The unique binding mode of LCA
provides clues for the development of new chemical compounds that
target alternative binding sites for therapeutic applications
Structural Basis for αâHelix Mimicry and Inhibition of ProteinâProtein Interactions with Oligourea Foldamers
A Vitamin D Receptor Selectively Activated by Gemini Analogs Reveals Ligand Dependent and Independent Effects
The bioactive form of vitamin D [1,25(OH)2D3] regulates mineral and bone homeostasis and exerts potent anti-inflammatory and antiproliferative properties through binding to the vitamin D receptor (VDR). The 3D structures of the VDR ligand-binding domain with 1,25(OH)2D3 or gemini analogs unveiled the molecular mechanism underlying ligand recognition. On the basis of structure-function correlations, we generated a point-mutated VDR (VDRgem) that is unresponsive to 1,25(OH)2D3, but the activity of which is efficiently induced by the gemini ligands. Moreover, we show that many VDR target genes are repressed by unliganded VDRgem and that mineral ion and bone homeostasis are more impaired in VDRgem mice than in VDR null mice, demonstrating that mutations abolishing VDR ligand binding result in more severe skeletal defects than VDR null mutations. As gemini ligands induce VDRgem transcriptional activity in mice and normalize their serum calcium levels, VDRgem is a powerful tool to further unravel both liganded and unliganded VDR signaling
Carborane-based design of a potent vitamin D receptor agonist
The vitamin D nuclear receptor (VDR) is a potential target for cancer therapy. It is expressed in many tumors and its ligand shows anticancer actions. To combine these properties with the application of boron neutron capture therapy (BNCT), we design and synthesize a potent VDR agonist based on the skeleton of the hormone 1 a,25-dihydroxyvitamin D3(1,25D) and an o -carborane (dicarba-o-closo-1,2-dodecaborane) at the end of its side chain. The present ligand is the first secosteroidal analog with the carborane unit that efficiently binds to VDR and functions as an agonist with 1,25D-like potency in transcriptional assay on
vitamin D target genes. Moreover it exhibits similar antiproliferative and pro-differentiating activities but is significantly less hypercalcemic than 1,25D. The crystal structure of its complex with VDR ligand binding domain reveals its binding mechanism involving boron-mediated dihydrogen bonds that mimic vitamin D hydroxyl interactions. In addition to the therapeutic interest, this study establishes the basis for the design of new unconventional vitamin D analogs containing carborane moieties for specific molecular recognition, and drug research and developmentWe thank the Spanish Ministry of Economy and Innovation
(MEI, SAF2010-15291 and SAF2012-38240), Xunta de Galicia
(project GPC2014/001), Agence Nationale de la Recherche (ANR-
13-BSV8-0024-01), French Infrastructure for Integrated Structural
Biology (FRISBI) (ANR-10-INSB-05-01), and INSTRUCT as
part of the European Strategy Forum on Research Infrastructures (ESFRI), for nancial support and CESGA for
computing time. R. O. thanks the Spanish MEI for an FPI
fellowship (BES-2011-0419192). S. S. thanks the AsociaciÂŽon
Espanola Contra el CĂĄncer for a fellowship (AIOA1101SEOA). R.
S. thanks the Xunta de Galicia for a postdoctoral fellowship
(POS-A/2012/112)S
Structural analysis and biological activities of C25-amino and C25-nitro vitamin D analogs
Intense synthetic efforts have been directed towards the development of noncalcemic analogs of 1,25-dihydroxyvitamin D3. We describe here the structural analysis and biological evaluation of two derivatives of 1,25-dihydroxyvitamin D3 with modifications limited to the replacement of the 25-hydroxyl group by a 25-amino or 25-nitro groups. Both compounds are agonists of the vitamin D receptor. They mediate biological effects similar to 1,25-dihydroxyvitamin D3, the 25-amino derivative being the most potent one while being less calcemic than 1,25-dihydroxyvitamin D3. The in vivo properties of the compounds make them of potential therapeutic value.Fil: GĂłmez BouzĂł, UxĂa. Universidad de Vigo. Facultad de Ciencias; EspañaFil: Belorusova, Anna Y.. UniversitĂ© de Strasbourg; Francia. Centre National de la Recherche Scientifique. Institut de gĂ©nĂ©tique et de biologie molĂ©culaire et cellulaire; FranciaFil: Rivadulla, Marcos Lois. Universidad de Vigo. Facultad de Ciencias; EspañaFil: Santalla, Hugo. Universidad de Vigo. Facultad de Ciencias; EspañaFil: Verlinden, Lieve. Katholikie Universiteit Leuven; BĂ©lgicaFil: Verstuyf, Annemieke. Katholikie Universiteit Leuven; BĂ©lgicaFil: Ferronato, MarĂa Julia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - BahĂa Blanca. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca. Universidad Nacional del Sur. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca; ArgentinaFil: Curino, Alejandro Carlos. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - BahĂa Blanca. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca. Universidad Nacional del Sur. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca; ArgentinaFil: Facchinetti, Maria Marta. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - BahĂa Blanca. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca. Universidad Nacional del Sur. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca; ArgentinaFil: Fall, Yagamare. Universidad de Vigo. Facultad de Ciencias; EspañaFil: GĂłmez, Generosa. Universidad de Vigo. Facultad de Ciencias; EspañaFil: Rochel, Natacha. Centre National de la Recherche Scientifique. Institut de gĂ©nĂ©tique et de biologie molĂ©culaire et cellulaire; Francia. UniversitĂ© de Strasbourg; Franci
Solution Behavior of the Intrinsically Disordered NâTerminal Domain of Retinoid X Receptor α in the Context of the Full-Length Protein
Retinoid X receptors (RXRs) are transcription
factors with important
functions in embryonic development, metabolic processes, differentiation,
and apoptosis. A particular feature of RXRs is their ability to act
as obligatory heterodimerization partners of class II nuclear receptors.
At the same time, these receptors are also able to form homodimers
that bind to direct repeat separated by one nucleotide hormone response
elements. Since the discovery of RXRs, most of the studies focused
on its ligand binding and DNA binding domains, while its N-terminal
domain (NTD) harboring a ligand-independent activation function remained
poorly characterized. Here, we investigated the solution properties
of the NTD of RXRα alone and in the context of the full-length
receptor using small-angle X-ray scattering and nuclear magnetic resonance
spectroscopy. We report the solution structure of the full-length
homodimeric RXRα on DNA and show that the NTD remains highly
flexible within this complex
1α,20S-Dihydroxyvitamin D3 Interacts with Vitamin D Receptor: Crystal Structure and Route of Chemical Synthesis
Abstract 1α,20S-Dihydroxyvitamin D3 [1,20S(OH)2D3], a natural and bioactive vitamin D3 metabolite, was chemically synthesized for the first time. X-ray crystallography analysis of intermediate 15 confirmed its 1α-OH configuration. 1,20S(OH)2D3 interacts with the vitamin D receptor (VDR), with similar potency to its native ligand, 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3] as illustrated by its ability to stimulate translocation of the VDR to the nucleus, stimulate VDRE-reporter activity, regulate VDR downstream genes (VDR, CYP24A1, TRPV6 and CYP27B1), and inhibit the production of inflammatory markers (IFNÎł and IL1ÎČ). However, their co-crystal structures revealed differential molecular interactions of the 20S-OH moiety and the 25-OH moiety to the VDR, which may explain some differences in their biological activities. Furthermore, this study provides a synthetic route for the synthesis of 1,20S(OH)2D3 using the intermediate 1α,3ÎČ-diacetoxypregn-5-en-20-one (3), and provides a molecular and biological basis for the development of 1,20S(OH)2D3 and its analogs as potential therapeutic agents