title: Comparative analysis of highly homologous Shewanella cytochromes c5 for stability and function.
abstract: Homologous cytochromes c(5) from a mesophile, Shewanella amazonensis (SA cytc(5)), and a psychrophile, Shewanella violacea (SV cytc(5)), were compared to elucidate the molecular mechanisms underlying protein stability and function. Cyclic voltammetry revealed that the two proteins had the same redox potential value. Differential scanning calorimetry showed that SV cytc(5) was more stable than SA cytc(5) in an enthalpic manner. These results and the structure model of Shewanella oneidensis cytochrome c(5) indicated that hydrophobic heme environments in the two proteins are the same to maintain the same redox potential value, and that the intra-molecular interactions in SV cytc(5), perhaps involved in Lys-50 and Tyr-73, account for its higher stability. Electron transfer from SV cytc(5) to membrane proteins of S. violacea and S. amazonensis was faster than that from SA cytc(5), suggesting that solvent-exposed Lys-4 in SV cytc(5) is responsible for the faster association and dissociation between SV cytc(5) and its redox partner.
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, CREST of Japan Science and Technology Corporation, Higashi-Hiroshima, Hiroshima, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Takenaka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Wakai
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Tamegai
authors.forename: Susumu
authors.initials: S
authors.lastname: Uchiyama
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sambongi
mesh_terms: D000595:Amino Acid Sequence; D003574:Cytochrome c Group / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D019897:Periplasm / Q000235:genetics; D011487:Protein Conformation; D011489:Protein Denaturation; D017386:Sequence Homology, Amino Acid; D020592:Shewanella / Q000201:enzymology* / Q000235:genetics; D013696:Temperature
chemical_list: D003574:Cytochrome c Group; C046450:cytochrome C5; D010088:Oxidoreductases