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. Study holds ProTherm entries: 10821, 10822, 10823, 10824 Extra Details: helical trigger segment; two-stranded coiled coil; surface salt bridge;,dimeric structure; hierarchic folding mechanism; local helix formation
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:41 p.m.
|Number of data points||4|
|Proteins||General control protein GCN4 ; General control protein GCN4|
|Assays/Quantities/Protocols||Experimental Assay: Tm|
|Libraries||Mutations for sequence RMKQLEDKVEELLSKNYHLENEVARLKKLVGER|