Kammerer R A, Jaravine V A, Frank S, Schulthess T, Landwehr R, Lustig A, Garcia-Echeverria C, Alexandrescu A T, Engel J, Steinmetz M O
Departments of Biophysical Chemistry and Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
J Biol Chem. 2001 Apr 27;276(17):13685-8. doi: 10.1074/jbc.M010492200. Epub 2000 Dec 27.
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.
我们之前报道过，GCN4亮氨酸拉链单体中的一个螺旋触发片段对于其平行双链卷曲螺旋的形成是不可或缺的。在此，我们证明触发位点的固有二级结构在很大程度上通过螺旋内盐桥得以稳定。通过单个氨基酸突变去除该表面盐桥，如经核磁共振验证，仅在GCN4亮氨酸拉链二聚体的主链结构中引起了微小变化。然而，该突变使二聚体结构大幅不稳定。这些发现支持了所提出的GCN4卷曲螺旋的分层折叠机制，其中触发片段内的局部螺旋形成先于二聚化。
