Amino acids 3–13 and amino acids in and flanking the ²³FxxLF²⁷ motif modulate the interaction between the N‐terminal and ligand‐binding domain of the androgen receptor

Abstract

The N-terminal domain (NTD) and the ligand-binding domain (LBD) of the androgen receptor (AR) exhibit a ligand-dependent interaction (N/C interaction). Amino acids 3-36 in the NTD (AR 3)36 ) play a dominant role in this interaction. Previously, it has been shown that a FxxFF motif in AR 3)36 , 23 FxxLF 27 , is essential for LBD interaction. We demonstrate in the current study that AR 3)36 can be subdivided into two functionally distinct fragments: AR 3)13 and AR 16)36 . AR 3)13 does not directly interact with the AR LBD, but rather contributes to the transactivation function of the AR.NTD-AR.LBD complex. AR 16)36, encompassing the 23 FxxLF 27 motif, is predicted to fold into a long amphipathic a-helix. A second FxxFF candidate protein interaction motif within the helical structure, 30 VREVI 34 , shows no affinity to the LBD. Within AR 16)36 , amino acid residues in and flanking the 23 FxxLF 27 motif are demonstrated to modulate N/C interaction. Substitution of Q24 and N25 by alanine residues enhances N/C interaction. Substitution of amino acids flanking the 23 FxxLF 27 motif by alanines are inhibitory to LBD interaction.

Dual Function of an Amino-terminal Amphipatic Helix in Androgen Receptor-mediated Transactivation through Specific and Nonspecific Response Elements

“…The deletion of the FQNLF motif in AR completely abolished the R1881-dependent interaction. These findings are in agreement with previous reports (40,41). Surprisingly, the G21E mutation in the NTD, outside the FQNLF motif, also markedly reduces N/C interaction.…”

“…already reported the involvement of one LXXLL-like motif, 179 LKDIL 183 (18), the mutation of which (I182A/L183A) impairs the N/C interaction and the activity of the AR. Two other candidate motives have been described: 23 FQNLF 27 and 432 WHTLF 436 (40,41). In this study, we performed a functional analysis of these latter motifs.…”

“…These N/C interactions have also been demonstrated in the progesterone receptor (44) and the estrogen receptor ␣ (45,46), but in these receptors the implication in receptor activity is less pronounced. The AR N/C interaction involves LKDIL and FQNLF core sequences, both present in predicted ␣-helical structures within the NTD (18,41). The FQNLF motif is located within the thirty aminoterminal amino acids of the AR and has the ability to bind AF-2 of the carboxyl-terminal domain in an androgen-dependent manner.…”

Intra-domain communication between the N-terminal and DNA-binding domains of the androgen receptor: modulation of androgen response element DNA binding

“…The results of the present study support the argument for intra-domain communication between the receptor NTD and DBD, with the former modulating DNA binding affinity. Interactions between the AR-NTD and the AR-LBD are well documented and known to be important for receptor function (see Steketee et al 2002. Mutagenesis analysis has highlighted a critical role for the first 21 amino acids of the AR-NTD and in particular the motif FqnLL (Steketee et al 2002.…”

Melanoma Antigen-A11 (MAGE-A11) Enhances Transcriptional Activity by Linking Androgen Receptor Dimers

“…Structure analysis indicates that AR amino acid residues carboxyl-terminal to helix 12 in the AR ligand binding domain project into the region involved in dimerization by other steroid receptor ligand binding domains (44). Instead, the region of AR proximal to AF2 is involved in stabilizing AR FXXLF motif binding by interacting with residues NH 2 -terminal to the AR FXXLF motif (60,61).…”