Rational design of a more stable yeast iso-1-cytochrome c.
Yeast iso-1-cytochrome c is one of the least stable mitochondrial cytochromes c. We have used a coordinated approach, combining the known functional and structural properties of cytochromes c, to engineer mutations into yeast iso-1-cytochrome c with the goal of selectively increasing the stability of the protein. The two redox forms of the native protein and six different mutant forms of yeast iso-1-cytochrome c were analyzed by differential scanning calorimetry (DSC). The relative stability, expressed as the difference in the Gibb's free energy of denaturation at a given temperature between the native and mutant forms (DeltaDeltaG(Tref)), was determined for each of the proteins. In both oxidation states, the mutant proteins C102T, T69E/C102T, T96A/C102T, and T69E/T96A/C102T were more stable than the wild-type protein, respectively. The increased stability of the mutant proteins is proposed to be due to the removal of a rare surface cysteine and the stabilization of two distorted alpha-helices.
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Department of Chemistry, University of Waterloo, Waterloo, Ont. N2L 3G1, Canada.
Rosu-Myles
M D
MD
Frey
H E
HE
Guillemette
J G
JG
D003574:Cytochrome c Group / Q000096:biosynthesis / Q000235:genetics*; D045304:Cytochromes c; D004795:Enzyme Stability / Q000235:genetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D017510:Protein Folding; D029701:Saccharomyces cerevisiae Proteins; D013816:Thermodynamics; D015003:Yeasts
C014059:CYC1 protein, S cerevisiae; D003574:Cytochrome c Group; D029701:Saccharomyces cerevisiae Proteins; D045304:Cytochromes c