Plasticity of the ecdysone receptor DNA binding domain.
Ecdysteroids coordinate molting and metamorphosis in insects via a heterodimer of two nuclear receptors, the ecdysone receptor (EcR) and the ultraspiracle (Usp) protein. Here we show how the DNA-recognition alpha-helix and the T box region of the EcR DNA-binding domain (EcRDBD) contribute to the specific interaction with the natural response element and to the stabilization of the EcRDBD molecule. The data indicate a remarkable mutational tolerance with respect to the DNA-binding function of the EcRDBD. This is particularly manifested in the heterocomplexes formed between the EcRDBD mutants and the wild-type Usp DNA-binding domain (UspDBD). Circular dichroism (CD) spectra and protein unfolding experiments indicate that, in contrast to the UspDBD, the EcRDBD is characterized by a lower alpha-helix content and a lower stability. As such, the EcRDBD appears to be an intrinsically unstructured protein-like molecule with a high degree of intramolecular plasticity. Because recently published crystal structures indicate that the ligand binding domain of the EcR is also characterized by the extreme adaptability, we suggest that plasticity of the EcR domains may be a key factor that allows a single EcR molecule to mediate diverse biological effects.
Orlowski
Marek
M
Institute of Organic Chemistry, Biochemistry and Biotechnology, Division of Biochemistry, Wrocław University of Technology, 50-370 Wrocław, Poland.
Szyszka
Monika
M
Kowalska
Agnieszka
A
Grad
Iwona
I
Zoglowek
Anna
A
Rymarczyk
Grzegorz
G
Dobryszycki
Piotr
P
Krowarsch
Daniel
D
Rastinejad
Fraydoon
F
Kochman
Marian
M
Ozyhar
Andrzej
A
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D018978:Molting / Q000235:genetics; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D017433:Protein Structure, Secondary / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D011987:Receptors, Steroid / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000099190:MAP-Kinase-Activated Kinase 2
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases; D011987:Receptors, Steroid; D014157:Transcription Factors; D000099190:MAP-Kinase-Activated Kinase 2; C066030:USP protein, Drosophila; C055469:ecdysone receptor