PDBsum entry 2ax6

Transcription

PDB id: 2ax6

Contents

Protein chain

242 a.a. *

Ligands

HFT

Waters ×200

* Residue conservation analysis

PDB id:

2ax6

Name:

Transcription

Title:

Crystal structure of the androgen receptor ligand binding domain t877a mutant in complex with hydroxyflutamide

Structure:

Androgen receptor. Chain: a. Fragment: ligand binding domain (residues 663-918). Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: ar. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.50Å R-factor: 0.246 R-free: 0.274

Authors:

C.E.Bohl,D.D.Miller,J.Chen,C.E.Bell,J.T.Dalton

Key ref:

C.E.Bohl et al. (2005). Structural basis for accommodation of nonsteroidal ligands in the androgen receptor. J Biol Chem, 280, 37747-37754. PubMed id: 16129672 DOI: 10.1074/jbc.M507464200

Date:

03-Sep-05 Release date: 20-Sep-05

Protein chain

P10275  (ANDR_HUMAN) -  Androgen receptor from Homo sapiens

Seq: 920 a.a.

Struc: 242 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1074/jbc.M507464200

J Biol Chem 280:37747-37754 (2005)

PubMed id: 16129672

Structural basis for accommodation of nonsteroidal ligands in the androgen receptor.

C.E.Bohl, D.D.Miller, J.Chen, C.E.Bell, J.T.Dalton.

ABSTRACT

The mechanism by which the androgen receptor (AR) distinguishes between agonist and antagonist ligands is poorly understood. AR antagonists are currently used to treat prostate cancer. However, mutations commonly develop in patients that convert these compounds to agonists. Recently, our laboratory discovered selective androgen receptor modulators, which structurally resemble the nonsteroidal AR antagonists bicalutamide and hydroxyflutamide but act as agonists for the androgen receptor in a tissue-selective manner. To investigate why subtle structural changes to both the ligand and the receptor (i.e. mutations) result in drastic changes in activity, we studied structure-activity relationships for nonsteroidal AR ligands through crystallography and site-directed mutagenesis, comparing bound conformations of R-bicalutamide, hydroxyflutamide, and two previously reported nonsteroidal androgens, S-1 and R-3. These studies provide the first crystallographic evidence of the mechanism by which nonsteroidal ligands interact with the wild type AR. We have shown that changes induced to the positions of Trp-741, Thr-877, and Met-895 allow for ligand accommodation within the AR binding pocket and that a water-mediated hydrogen bond to the backbone oxygen of Leu-873 and the ketone of hydroxyflutamide is present when bound to the T877A AR variant. Additionally, we demonstrated that R-bicalutamide stimulates transcriptional activation in AR harboring the M895T point mutation. As a whole, these studies provide critical new insight for receptor-based drug design of nonsteroidal AR agonists and antagonists.

Selected figure(s)

Figure 5.
FIGURE 5. Ligand-induced changes to Trp-741 and Met-895 in stereo overlay and individually as space-fill representations. a, comparison of the changes induced by DHT (slate) (Protein Data Bank code 1I37 [PDB] ), R1881 (ruby) (Protein Data Bank code 1XQ2), R-3 (gold), and S-1 (green) to the Trp-741, Met-745, Met-895 side chains. Notice the different location of Met-745 in the DHT-bound structure from displacement by the 19-methyl group, which causes the Trp-741 side chain to also move relative to its position in R1881. The Trp-741 indole ring is positioned similarly in R1881- and R-3-complexed structures; however, the bromine atom on R-3 displaces the Met-895 side chain. Also notice the change in position of the Trp-741 indole ring to allow accommodation of the S-1 B-ring. b, changes in the position of Met-895 in the W741L AR bound to S-1 (black) and R-bicalutamide (yellow). Compared with the WT-S-1 complex, Met-895 moves toward the Leu-741 side chain in the W741L-S-1 complex, compensating for the loss of bulk in this mutant. In the W741L-R-bicalutamide complex, the Met-895 side chain is wedged between the Leu-741 and the sulfonyl group of R-bicalutamide. Notice that the position of the Met-895 side chain in the WT-S-1 complex would be sterically precluded by the sulfonyl group of R-bicalutamide in the presence of Trp-741.

Figure 6.
FIGURE 6. Ligand interactions with helices 3, 5, 11, and 12. a, WT AR LBD complexed to S-1 (green) rotated 180° about the y-axis relative to Fig. 3, c and d. Helix 3, blue; helices 4/5, Trp741, purple; helix 11, Thr-877, red; helix 12, Met-895, gold. b, surface contacts of the secondary structural elements of the WT AR LBD with S-1. Notice the contacts from Trp-741, Thr-877, and Met-895 on helices 5, 11, and 12, respectively. c, surface contacts of the secondary structural elements of the W741L AR LBD with R-bicalutamide. Notice the loss of contacts of helix 5 from the loss of bulk in the W741L mutant and that helix 12 increases contacts to the ligand as a result of Met-895 repositioning. Also notice the location of the sulfonyl group of R-bicalutamide, which increases the binding pocket size relative to S-1.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2005, 280, 37747-37754) copyright 2005.

Figures were selected by an automated process.