J S Merkel1, L Regan. 1. Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA.
Abstract
BACKGROUND: Glycine is an intrinsically destabilizing residue in beta sheets. In natural proteins, however, this destabilization can be 'rescued' by specific cross-strand pairing with aromatic residues. Here, we present an experimental study of this effect. RESULTS: Protein variants containing glycine and aromatic residues positioned across beta strands in both antiparallel and parallel orientations were studied. The pairing of glycine and phenylalanine across antiparallel strands resulted in a synergistic increase in protein stability. Dramatic differences in stability were observed for the parallel beta-sheet mutants, which were dependent upon the type of site occupied by glycine as well as the type of aromatic residue with which it was cross-strand paired. CONCLUSIONS: Experimental results from a series of mutants suggest a thermodynamic benefit for glycine-aromatic pairing across antiparallel beta strands, consistent with the prevalence of such pairs in natural proteins. We also demonstrate the specificity of glycine-aromatic interactions across parallel beta strands, which defines strand register.
BACKGROUND:Glycine is an intrinsically destabilizing residue in beta sheets. In natural proteins, however, this destabilization can be 'rescued' by specific cross-strand pairing with aromatic residues. Here, we present an experimental study of this effect. RESULTS: Protein variants containing glycine and aromatic residues positioned across beta strands in both antiparallel and parallel orientations were studied. The pairing of glycine and phenylalanine across antiparallel strands resulted in a synergistic increase in protein stability. Dramatic differences in stability were observed for the parallel beta-sheet mutants, which were dependent upon the type of site occupied by glycine as well as the type of aromatic residue with which it was cross-strand paired. CONCLUSIONS: Experimental results from a series of mutants suggest a thermodynamic benefit for glycine-aromatic pairing across antiparallel beta strands, consistent with the prevalence of such pairs in natural proteins. We also demonstrate the specificity of glycine-aromatic interactions across parallel beta strands, which defines strand register.
Authors: Bipasha Barua; Jasper C Lin; Victoria D Williams; Phillip Kummler; Jonathan W Neidigh; Niels H Andersen Journal: Protein Eng Des Sel Date: 2008-01-18 Impact factor: 1.650