Activity-stability relationships revisited in blue oxidases catalyzing electron transfer at extreme temperatures.
Cuproxidases are a subset of the blue multicopper oxidases that catalyze the oxidation of toxic Cu(I) ions into less harmful Cu(II) in the bacterial periplasm. Cuproxidases from psychrophilic, mesophilic, and thermophilic bacteria display the canonical features of temperature adaptation, such as increases in structural stability and apparent optimal temperature for activity with environmental temperature as well as increases in the binding affinity for catalytic and substrate copper ions. In contrast, the oxidative activities at 25 °C for both the psychrophilic and thermophilic enzymes are similar, suggesting that the nearly temperature-independent electron transfer rate does not require peculiar adjustments. Furthermore, the structural flexibilities of both the psychrophilic and thermophilic enzymes are also similar, indicating that the firm and precise bindings of the four catalytic copper ions are essential for the oxidase function. These results show that the requirements for enzymatic electron transfer, in the absence of the selective pressure of temperature on electron transfer rates, produce a specific adaptive pattern, which is distinct from that observed in enzymes possessing a well-defined active site and relying on conformational changes such as for the induced fit mechanism.
Laboratory of Biochemistry, Center for Protein Engineering, University of Liège, Liège, Belgium.
Frédéric
F
Roulling
Laboratory of Biochemistry, Center for Protein Engineering, University of Liège, Liège, Belgium.
Amandine
A
Godin
Laboratory of Biochemistry, Center for Protein Engineering, University of Liège, Liège, Belgium.
Alexandre
A
Cipolla
Department of Biology, Center of Molecular and Environmental Biology, University of Minho, Braga, Portugal.
Tony
T
Collins
Department of Life Science and Biotechnology, Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan.
Kentaro
K
Miyazaki
Laboratory of Biochemistry, Center for Protein Engineering, University of Liège, Liège, Belgium. gfeller@ulg.ac.be.
Georges
G
Feller
D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D003080:Cold Temperature; D004579:Electron Transport; D004795:Enzyme Stability; D006358:Hot Temperature; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D031161:Pseudoalteromonas / Q000201:enzymology; D016963:Thermus thermophilus / Q000201:enzymology
D001426:Bacterial Proteins; D010088:Oxidoreductases; C024748:copper oxidase
Cuproxidase; Electron transfer; Multicopper oxidase; Psychrophiles; Thermophiles