1KFN: Core Side-Chain Packing And Backbone Conformation In Lpp-56 Coiled- Coil Mutants

Native proteins exhibit precise geometric packing of atoms in their hydrophobic interiors. Nonetheless, controversy remains about the role of core side-chain packing in specifying and stabilizing the folded structures of proteins. Here we investigate the role of core packing in determining the conformation and stability of the Lpp-56 trimerization domain. The X-ray crystal structures of Lpp-56 mutants with alanine substitutions at two and four interior core positions reveal trimeric coiled coils in which the twist of individual helices and the helix-helix spacing vary significantly to achieve the most favored superhelical packing arrangement. Introduction of each alanine "layer" into the hydrophobic core destabilizes the superhelix by 1.4 kcal mol(-1). Although the methyl groups of the alanine residues pack at their optimum van der Waals contacts in the coiled-coil trimer, they provide a smaller component of hydrophobic interactions than bulky hydrophobic side-chains to the thermodynamic stability. Thus, specific side-chain packing in the hydrophobic core of coiled coils are important determinants of protein main-chain conformation and stability.
PDB ID: 1KFNDownload
MMDB ID: 19851
PDB Deposition Date: 2001/11/21
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 1.65  Å
Source Organism:
Similar Structures:
Biological Unit for 1KFN: trimeric; determined by author and by software (PISA,PQS)
Molecular Components in 1KFN
Label Count Molecule
Proteins (3 molecules)
Major Outer Membrane Lipoprotein(Gene symbol: lpp)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB