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Updated: Aug 14, 2026

A G-quadruplex DNA-affinity Approach for Purification of Enzymatically Active G4 Resolvase1
Published on: March 18, 2017
An intrahelical salt bridge within the trigger site stabilizes the GCN4 leucine zipper
R A Kammerer1, V A Jaravine, S Frank
1Departments of Biophysical Chemistry and Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
Abstract:
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.
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