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Crystal structure of a synthetic triple-stranded alpha-helical bundle
1Molecular Biology Institute, University of California, Los Angeles 90024-1570.
Science (New York, N.Y.)
|February 26, 1993
Summary
A designed peptide unexpectedly formed a triple-stranded coiled coil, not the intended double-stranded structure. This reveals the crucial role of hydrophobic interactions in stabilizing coiled-coil protein structures.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Design
Background:
- Coiled coils are common protein structural motifs.
- Designing specific coiled coil structures is challenging.
- Understanding factors stabilizing coiled coils is key for protein engineering.
Purpose of the Study:
- To determine the x-ray crystal structure of a peptide designed to form a double-stranded parallel coiled coil.
- To investigate the structural basis of coiled coil formation and stability.
Main Methods:
- X-ray crystallography
- Peptide design and synthesis
- Structural analysis
Main Results:
- The designed peptide formed an unexpected triple-stranded coiled coil.
- The helices adopted an up-up-down orientation, differing from the designed parallel structure.
- A stable hydrophobic interface with eight layers, involving leucine side chains, was identified.
- Hydrophobic interactions were found to be a major stabilizing factor.
Conclusions:
- Hydrophobic interactions are critical for stabilizing coiled coil structures.
- Side chain packing in the hydrophobic core dictates stoichiometry and geometry.
- Electrostatic interactions also play a role in coiled coil stability.