Selected mutations in a mesophilic cytochrome c confer the stability of a thermophilic counterpart.
Mesophilic cytochrome c(551) of Pseudomonas aeruginosa (PA c(551)) became as stable as its thermophilic counterpart, Hydrogenobacter thermophilus cytochrome c(552) (HT c(552)), 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 c(552) through careful structure comparison. Thermodynamic analysis indicated that the stability of the quintuple mutant of PA c(551) could be partly attained through an enthalpic factor. The solution structure of the mutant showed that, as in HT c(552), 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.
Daiichi Pharmaceutical Co., Ltd., Edogawa-ku, Tokyo 134-8630, Japan. haseg7li@daiichipharm.co.jp
J
J
Hasegawa
S
S
Uchiyama
Y
Y
Tanimoto
M
M
Mizutani
Y
Y
Kobayashi
Y
Y
Sambongi
Y
Y
Igarashi
D001419:Bacteria / Q000201:enzymology*; D001426:Bacterial Proteins; D003574:Cytochrome c Group / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D011489:Protein Denaturation; D011550:Pseudomonas aeruginosa / Q000201:enzymology*; D013696:Temperature
D001426:Bacterial Proteins; D003574:Cytochrome c Group; C017167:cytochrome C(551)