Biochemical Characterization of DpcA from Psychrobacter cryohalolentis K5: The First Extremophilic Member of the Haloalkane Dehalogenase Family
Ivana Drienovská1, Eva Chovancová1, Táňa Koudeláková1, Jiří
Damborský12 and Radka Chaloupková1
1Loschmidt
Laboratories, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment,
Faculty of Science, Masaryk University, Kamenice
5/A4, 625 00 Brno, 2International Clinical Research Center, St.
Anne's University Hospital, 656 91 Brno
drienovska@mail.muni.cz
Haloalkane dehalogenases (HLDs, EC 3.8.1.5) are microbial enzymes which catalyze the hydrolysis of a carbon-halogen bond in halogenated aliphatic hydrocarbons, releasing a halide ion and a corresponding alcohol, as the reaction products. HLDs catalyze the reactions of great environmental and biotechnological significance with potential application in the bioremediation, the biosensing, the decontamination of warfare agents, the synthesis of optically pure compounds, the cellular imaging and the protein tagging. The effective use of biocatalysts in these applications requires availability of enzymes with specific properties under harsh process conditions. Such properties can be easily obtained by isolation of novel biocatalysts from the extremophiles, producing the enzymes called extremozymes. These enzymes are able to operate under extreme conditions such as high or low temperature, high or low pH, pressure or high salinity.
This study describes identification, isolation and biochemical
characterization of a novel haloalkane dehalogenase DpcA from Psychrobacter cryohalolentis K5,
representing the first extremophilic member of the haloalkane dehalogenase family. This
enzyme was purified to homogeneity by metaloaffinity
chromatography and biochemically characterized. Correct folding of DpcA was verified by the circular dichroism
spectroscopy. Substrate specificity of the enzyme was tested towards thirty different
halogenated compounds to confirm its dehalogenase
activity. DpcA exhibited one of the narrowest
substrate specificity profiles from all biochemically characterized HLDs. It was
most active towards 1,3-dibromopropane, 1-bromohexane
and 1-bromobutane, generally preferred brominated and
terminally substituted substrates. Compared to other HLDs, DpcA
has the lowest thermostability (Tm = 34.7 ±
This work was supported by the European Regional Development Fund (CZ.1.05/2.1.00/01.0001 and CZ.1.05/1.1.00/02.0123), the Grant Agency of the Czech Republic (P202/10/1435 and P207/12/0775) and the Grant Agency of the Czech Academy of Sciences (IAA401630901).