An intrahelical salt bridge within the trigger site stabilizes the GCN4 leucine zipper.
We previously reported that a helical trigger segment within the GCN4 leucine zipper monomer is indispensable for the formation of its parallel two-stranded coiled coil. Here, we demonstrate that the intrinsic secondary structure of the trigger site is largely stabilized by an intrahelical salt bridge. Removal of this surface salt bridge by a single amino acid mutation induced only minor changes in the backbone structure of the GCN4 leucine zipper dimer as verified by nuclear magnetic resonance. The mutation, however, substantially destabilized the dimeric structure. These findings support the proposed hierarchic folding mechanism of the GCN4 coiled coil in which local helix formation within the trigger segment precedes dimerization.
Kammerer
R A
RA
Departments of Biophysical Chemistry and Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
Jaravine
V A
VA
Frank
S
S
Schulthess
T
T
Landwehr
R
R
Lustig
A
A
Garcia-Echeverria
C
C
Alexandrescu
A T
AT
Engel
J
J
Steinmetz
M O
MO
D000409:Alanine / Q000737:chemistry; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D001120:Arginine / Q000737:chemistry; D004268:DNA-Binding Proteins; D019281:Dimerization; D004926:Escherichia coli / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics; D018698:Glutamic Acid / Q000737:chemistry; D016350:Leucine Zippers; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010957:Plasmids / Q000378:metabolism; D011487:Protein Conformation; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics; D017433:Protein Structure, Secondary; D029701:Saccharomyces cerevisiae Proteins; D012492:Salts / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology
D000596:Amino Acids; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D012492:Salts; D018698:Glutamic Acid; D012965:Sodium Chloride; D001120:Arginine; D011494:Protein Kinases; D000409:Alanine