1kfn
From Proteopedia
Core side-chain packing and backbone conformation in Lpp-56 coiled-coil mutants
Overview
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.
About this Structure
1KFN is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Core side-chain packing and backbone conformation in Lpp-56 coiled-coil mutants., Liu J, Cao W, Lu M, J Mol Biol. 2002 May 3;318(3):877-88. PMID:12054830 Page seeded by OCA on Fri May 2 22:41:22 2008
