Nature Structural Biology
3, 54 - 58 (1996)
doi:10.1038/nsb0196-54
Amino-acid substitutions in a surface turn modulate protein stabilityPaul F. Predki1, Vishal Agrawal2, Axel T. Brünger2
& Lynne Regan3
1Present address: CuraGen Corporation Branford, Connecticut 06405, USA
2Howard Hughes Medical Institute Yale University, New Haven, Connecticut 06520, USA
3Department of Molecular Biophysics and Biochemistry Yale University, New Haven, Connecticut 06520, USA A surface turn position in a four-helix bundle protein, Rop, was selected to investigate the role of turns in protein structure and stability. Although all twenty amino acids can be substituted at this position to generate a correctly folded protein, they produce an unusually large range of thermodynamic stabilities. Moreover, the majority of substitutions give rise to proteins with enhanced thermal stability compared to that of the wild type. By introducing the same twenty mutations at this position, but in a simplified context, we were able to deconvolute intrinsic preferences from local environmental effects. The intrinsic preferences can be explained on the basis of preferred backbone dihedral angles, but local environmental context can significantly modify these effects.
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