Structure-function-folding relationship in a WW domain.Jager, M., Zhang, Y., Bieschke, J., Nguyen, H., Dendle, M., Bowman, M.E., Noel, J.P., Gruebele, M., Kelly, J.W.
(2006) Proc.Natl.Acad.Sci.Usa 103: 10648-10653
- PubMed: 16807295
- DOI: 10.1073/pnas.0600511103
- Primary Citation of Related Structures:
- PubMed Abstract:
Protein folding barriers result from a combination of factors including unavoidable energetic frustration from nonnative interactions, natural variation and selection of the amino acid sequence for function, and/or selection pressure against aggregat ...
Protein folding barriers result from a combination of factors including unavoidable energetic frustration from nonnative interactions, natural variation and selection of the amino acid sequence for function, and/or selection pressure against aggregation. The rate-limiting step for human Pin1 WW domain folding is the formation of the loop 1 substructure. The native conformation of this six-residue loop positions side chains that are important for mediating protein-protein interactions through the binding of Pro-rich sequences. Replacement of the wild-type loop 1 primary structure by shorter sequences with a high propensity to fold into a type-I' beta-turn conformation or the statistically preferred type-I G1 bulge conformation accelerates WW domain folding by almost an order of magnitude and increases thermodynamic stability. However, loop engineering to optimize folding energetics has a significant downside: it effectively eliminates WW domain function according to ligand-binding studies. The energetic contribution of loop 1 to ligand binding appears to have evolved at the expense of fast folding and additional protein stability. Thus, the two-state barrier exhibited by the wild-type human Pin1 WW domain principally results from functional requirements, rather than from physical constraints inherent to even the most efficient loop formation process.
Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, BCC265, La Jolla, CA 92037, USA.