Engineering a two-helix bundle protein for folding studies.
The SAP domain from the Saccharomyces cerevisiae THO1 protein contains a hydrophobic core and just two alpha-helices. It could provide a system for studying protein folding that bridges the gap between studies on isolated helices and those on larger protein domains. We have engineered the SAP domain for protein folding studies by inserting a tryptophan residue into the hydrophobic core (L31W) and solved its structure. The helical regions had a backbone root mean-squared deviation of 0.9 A from those of wild type. The mutation L31W destabilised wild type by 0.8 +/- 0.1 kcal mol(-1). The mutant folded in a reversible, apparent two-state manner with a microscopic folding rate constant of around 3700 s(-1) and is suitable for extended studies of folding.
MRC Centre for Protein Engineering, Hills Road, Cambridge CB20QH, UK.
Charlotte A
CA
Dodson
Neil
N
Ferguson
Trevor J
TJ
Rutherford
Christopher M
CM
Johnson
Alan R
AR
Fersht
D007700:Kinetics; D008958:Models, Molecular; D020125:Mutation, Missense / Q000235:genetics; D015202:Protein Engineering / Q000379:methods*; D017510:Protein Folding; D017433:Protein Structure, Secondary / Q000235:genetics*; D017434:Protein Structure, Tertiary / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*
D029701:Saccharomyces cerevisiae Proteins