title: Cold adapted features of Vibrio salmonicida catalase: characterisation and comparison to the mesophilic counterpart from Proteus mirabilis.
abstract: The gene encoding catalase from the psychrophilic marine bacterium Vibrio salmonicida LFI1238 was identified, cloned and expressed in the catalase-deficient Escherichia coli UM2. Recombinant catalase from V. salmonicida (VSC) was purified to apparent homogeneity as a tetramer with a molecular mass of 235 kDa. VSC contained 67% heme b and 25% protoporphyrin IX. VSC was able to bind NADPH, react with cyanide and form compounds I and II as other monofunctional small subunit heme catalases. Amino acid sequence alignment of VSC and catalase from the mesophilic Proteus mirabilis (PMC) revealed 71% identity. As for cold adapted enzymes in general, VSC possessed a lower temperature optimum and higher catalytic efficiency (k (cat)/K (m)) compared to PMC. VSC have higher affinity for hydrogen peroxide (apparent K (m)) at all temperatures. For VSC the turnover rate (k (cat)) is slightly lower while the catalytic efficiency is slightly higher compared to PMC over the temperature range measured, except at 4 degrees C. Moreover, the catalytic efficiency of VSC and PMC is almost temperature independent, except at 4 degrees C where PMC has a twofold lower efficiency compared to VSC. This may indicate that VSC has evolved to maintain a high efficiency at low temperatures.
authors.affiliation: Department of Molecular Biotechnology, Faculty of Medicine, Institute of Medical Biology, University of Tromsø, 9037 Tromsø, Norway.
authors.forename: Marit Sjo
authors.initials: MS
authors.lastname: Lorentzen
authors.forename: Elin
authors.initials: E
authors.lastname: Moe
authors.forename: Hélène Marie
authors.initials: HM
authors.lastname: Jouve
authors.forename: Nils Peder
authors.initials: NP
authors.lastname: Willassen
mesh_terms: D000222:Adaptation, Physiological; D044165:Aliivibrio salmonicida / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D000595:Amino Acid Sequence; D001483:Base Sequence; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D003080:Cold Temperature; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D011513:Proteus mirabilis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D004269:DNA, Bacterial; D002374:Catalase