Open AccessThe first structure of a cold‐adapted superoxide dismutase (SOD): biochemical and structural characterization of iron SOD from Aliivibrio salmonicida
Author(s) -
Pedersen Hege Lynum,
Willassen Nils Peder,
Leiros Ingar
Publication year - 2009
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309109001110
Subject(s) - superoxide dismutase , chemistry , characterization (materials science) , biochemistry , enzyme , microbiology and biotechnology , biology , materials science , nanotechnology
Superoxide dismutases (SODs) are metalloenzymes that catalyse the dismutation of the superoxide radical anion into O 2 and H 2 O 2 in a two‐step reaction. The crystal structure of the iron superoxide dismutase from the cold‐adapted and fish‐pathogenic bacterium Aliivibrio salmonicida (asFeSOD) has been determined and refined to 1.7 Å resolution. The protein has been characterized and compared with the closely related homologous iron superoxide dismutase from the mesophilic Escherichia coli (ecFeSOD) in an attempt to rationalize its environmental adaptation. ecFeSOD shares 75% identity with asFeSOD. Compared with the mesophilic FeSOD, the psychrophilic FeSOD has distinct temperature differences in residual activity and thermostability that do not seem to be related to structural differences such as intramolecular or intermolecular ion bonds, hydrogen bonds or cavity sizes. However, an increased net negative charge on the surface of asFeSOD may explain its lower thermostability compared with ecFeSOD. Activity measurements and differential scanning calorimetry measurements revealed that the psychrophilic asFeSOD had a thermostability that was significantly higher than the optimal growth temperature of the host organism.