Characterization of the Nurr1 ligand-binding domain co-activator interaction surface.
The recently solved crystal structure of the orphan nuclear receptor (NR) Nurr1 ligand-binding domain (LBD) showed that Nurr1 lacks a cavity for ligand binding and a canonical NR co-activator-binding site. Computer modeling of the Nurr1 LBD structure identified a hydrophobic region on the surface of the Nurr1 LBD that was positioned on the opposite side from the classical co-activator-binding site. Site-directed mutagenesis demonstrated that this region is critical for the activity of the Nurr1 LBD. Most mutations introduced in this region reduced or abolished transcriptional activity of the Nurr1 LBD, but mutation at lysine (K577) resulted in a drastically increased activity. Moreover, the activity of the Nurr1 LBD was shown to correlate with a propensity for proteasome-dependent degradation revealing a close association between activity and Nurr1 protein turnover. These data provide novel insights into the mechanisms of transcription via the Nurr1 LBD and identify an alternative co-activator-binding surface that is unique to the NR4A family of NRs.
Volakakis
Nikolaos
N
Ludwig Institute for Cancer Research, Stockholm Branch, Box 240, S-171 77 Stockholm, Sweden.
Malewicz
Michal
M
Kadkhodai
Banafsheh
B
Perlmann
Thomas
T
Benoit
Gerard
G
D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019281:Dimerization; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D009154:Mutation; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D009928:Organ Specificity; D011485:Protein Binding; D011489:Protein Denaturation / Q000502:physiology; D017434:Protein Structure, Tertiary; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D047488:Retinoid X Receptors / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008024:Ligands; C539882:NR4A2 protein, human; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D018160:Receptors, Cytoplasmic and Nuclear; D047488:Retinoid X Receptors; D014157:Transcription Factors