Dissociation and unfolding of GCN4 leucine zipper in the presence of sodium dodecyl sulfate.
The dissociation and unfolding behavior of the GCN4 leucine zipper has been studied using SDS titration. Circular dichroism (CD) spectra showed that the alpha-helix content of the leucine zipper (20 microM) decreased during the sodium dodecyl sulfate (SDS) titration. However, the alpha-helix content of the leucine zipper still remained significant in the presence of 1 mM SDS, with little change detected when the SDS concentration further increased to 2 mM. The dimer dissociation of the leucine zipper is also a co-operative process during SDS titration; with no dimer remaining when SDS concentration reached 1 mM, as shown by electrophoresis and the the theta(222)/theta(208) ratio. Our results indicate that SDS efficiently induces leucine zipper dimer dissociation with the monomers still partially folded. The experimental results provide important evidence for the previous model that partial helix formation precedes dimerization in coiled coil folding.
Meng
F G
FG
Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China.
Zeng
X
X
Hong
Y K
YK
Zhou
H M
HM
D002942:Circular Dichroism; D004268:DNA-Binding Proteins; D019281:Dimerization; D005656:Fungal Proteins / Q000737:chemistry*; D016350:Leucine Zippers / Q000187:drug effects*; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding; D011494:Protein Kinases / Q000737:chemistry*; D017433:Protein Structure, Secondary; D029701:Saccharomyces cerevisiae Proteins; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology*
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D012967:Sodium Dodecyl Sulfate; D011494:Protein Kinases