Download MendeleyCore side-chain packing and backbone conformation in Lpp-56 coiled-coil mutants.
Liu, J., Cao, W., Lu, M.(2002) J Mol Biol 318: 877-888
- PubMed: 12054830
- DOI: https://doi.org/10.1016/S0022-2836(02)00138-9
- Primary Citation of Related Structures:
1KFM, 1KFN - PubMed Abstract:
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.
Organizational Affiliation:
Department of Biochemistry, Weill Medical College of Cornell University, New York, NY 10021, USA.
