Dioxane contributes to the altered conformation and oligomerization state of a designed engrailed homeodomain variant.
Our goal was to compute a stable, full-sequence design of the Drosophila melanogaster engrailed homeodomain. Thermal and chemical denaturation data indicated the design was significantly more stable than was the wild-type protein. The data were also nearly identical to those for a similar, later full-sequence design, which was shown by NMR to adopt the homeodomain fold: a three-helix, globular monomer. However, a 1.65 A crystal structure of the design described here turned out to be of a completely different fold: a four-helix, rodlike tetramer. The crystallization conditions included approximately 25% dioxane, and subsequent experiments by circular dichroism and sedimentation velocity analytical ultracentrifugation indicated that dioxane increases the helicity and oligomerization state of the designed protein. We attribute at least part of the discrepancy between the target fold and the crystal structure to the presence of a high concentration of dioxane.
Hom
Geoffrey K
GK
Biochemistry and Molecular Biophysics Option, California Institute of Technology/HHMI 114-96, 1200 E. California Boulevard, Pasadena, CA 91125-9600, USA.
Lassila
J Kyle
JK
Thomas
Leonard M
LM
Mayo
Stephen L
SL
D000818:Animals; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D004146:Dioxanes / Q000737:chemistry / Q000494:pharmacology*; D029721:Drosophila Proteins; D018398:Homeodomain Proteins / Q000737:chemistry*; D008958:Models, Molecular; D011487:Protein Conformation / Q000187:drug effects; D014157:Transcription Factors / Q000737:chemistry*
D004146:Dioxanes; D029721:Drosophila Proteins; C063459:En protein, Drosophila; D018398:Homeodomain Proteins; D014157:Transcription Factors; C025223:1,4-dioxane
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