Stabilization Mechanism of Cytochromec552from a Moderately Thermophilic Bacterium,Hydrogenophilus thermoluteolus

Sayaka HAKAMADA, Takafumi SONOYAMA, Shin-ichi ICHIKI, Shota NAKAMURA, Susumu UCHIYAMA, Yuji KOBAYASHI, Yoshihiro SAMBONGI
2008 Bioscience, biotechnology and biochemistry  
Cytochrome c 552 (PH c 552 ) from moderately thermophilic Hydrogenophilus thermoluteolus exhibits stability intermediate between those of cytochrome c 552 (HT c 552 ) from thermophilic Hydrogenobacter thermophilus and cytochrome c 551 (PA c 551 ) from mesophilic Pseudomonas aeruginosa. To understand the mechanism of stabilization of PH c 552 , we introduced mutations into PH c 552 at five sites, which, in HT c 552 , are occupied by the amino acids responsible for stability higher than the less
more » ... gher than the less stable PA c 551 . When PH c 552 Val-78 was mutated to Ile, as found in HT c 552 , the resulting variant showed increased stability. Mutation of Ala-7, Met-13, and Tyr-34 to the corresponding residues in PA c 551 (Phe, Val, and Phe, respectively) resulted in destabilization. We also found that PH c 552 Lys-43 contributed to stability through the formation of an attractive electrostatic interaction with Asp-39. These results suggest that the intermediate stability of PH c 552 is due to the amino acids at these five sites.
doi:10.1271/bbb.80187 pmid:18685221 fatcat:woi2r27blfedlb435p55bpil6e