title: Physiological role and redox properties of a small cytochrome c(5), cytochrome c-552, from alkaliphile, Pseudomonas alcaliphila AL15-21(T).
abstract: Cytochrome c-552 from Pseudomonas alcaliphila AL15-21(T), which is a small cytochrome c(5) from Pseudomonas spp., was first purified and characterized in our previous study. Although it has been found that cytochrome c-552 is induced at a high pH under air-limited condition, the physiological role of this cytochrome c has not been clarified yet. Therefore, to understand its physiological role, further characterization of this cytochrome expressed in Escherichia coli was performed. The yield of the recombinant protein reached 2.8 mg/l of culture, which was 76.4-fold larger than that of native cells. Analytical data of the recombinant protein exactly agreed with that of native cytochrome c-552. The recombinant cytochrome c-552 was oxidized by partially purified cb-type cytochrome c oxidase from P. alcaliphila AL15-21(T) at a rate of 9.6 mu mol min(-1) mg oxidase(-1). Unlike reported cytochromes c from other Pseudomonas spp., the E degrees ' values between pHs 5.0 and 10.0 were nearly unchanged. Cytochrome c-552 oxidized very slowly at pHs 8.0 (6.1 x 10(-4) h(-1)), 9.0 (1.4 x 10(-3) h(-1)) and 10.0 (1.6 x 10(-3) h(-1)), whereas it oxidized more rapidly at pH 7.0 (2.5 x 10(-3) h(-1)). On the other hand, horse heart cytochrome c showed higher oxidation rates at pHs 6.0-10.0 than cytochrome c-552. It is considered that the high electron-retaining ability of cytochrome c-552 at high pHs is important for its physiological function in the environmental adaptation of this bacteria for superior growth at high pHs under air-limited conditions.
authors.affiliation: Research Institute of Genome-based Biofactory, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo 062-8517, Japan.
authors.forename: Toshihide
authors.initials: T
authors.lastname: Matsuno
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Mie
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Yoshimune
authors.forename: Isao
authors.initials: I
authors.lastname: Yumoto
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D003574:Cytochrome c Group / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000378:metabolism; D004734:Energy Metabolism; D004926:Escherichia coli / Q000378:metabolism; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D011199:Potentiometry; D011487:Protein Conformation; D017510:Protein Folding; D011549:Pseudomonas / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012995:Solubility; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D003574:Cytochrome c Group; C022302:cytochrome C-552; D003576:Electron Transport Complex IV