Title
Selected Mutations in a Mesophilic Cytochrome cConfer the Stability of a Thermophilic Counterpart
Author
Jun Hasegawa, Susumu Uchiyama, Yuko Tanimoto, Masayuki Mizutani, Yuji Kobayashi, Yoshihiro Sambongi, Yasuo Igarashi
Year
2000
Journal
The Journal of Biological Chemistry
Abstract
Mesophilic cytochrome c551 of Pseudomonas aeruginosa (PA c551) became as stable as its thermophilic counterpart, Hydrogenobacter thermophilus cytochrome c552 (HT c552), through only five amino acid substitutions. The five residues, distributed in three spatially separated regions, were selected and mutated with reference to the corresponding residues in HT c552 through careful structure comparison. Thermodynamic analysis indicated that the stability of the quintuple mutant of PA c551 could be partly attained through an enthalpic factor. The solution structure of the mutant showed that, as in HT c552, there were tighter side chain packings in the mutated regions. Furthermore, the mutant had an increased total accessible surface area, resulting in great negative hydration free energy. Our results provide a novel example of protein stabilization in that limited amino acid substitutions can confer the overall stability of a natural highly thermophilic protein upon a mesophilic molecule.
Full Article
Instrument
J-720
Keywords
Circular dichroism, Secondary structure, Protein denaturation, Thermodynamics, Thermal stability, Biochemistry