Pudnikova_2019_Crystals_9_375

Haloalkane dehalogenases are a very important class of microbial enzymes for environmental detoxification of halogenated pollutants, for biocatalysis, biosensing and molecular tagging. The double mutant (Ile44Leu + Gln102His) of the haloalkane dehalogenase DbeA from Bradyrhizobium elkanii USDA94 (DbeADCl) was constructed to study the role of the second halide-binding site previously discovered in the wild-type structure. The variant is less active, less stable in the presence of chloride ions and exhibits significantly altered substrate specificity when compared with the DbeAwt. DbeADCl was crystallized using the sitting-drop vapour-diffusion procedure with further optimization by the random microseeding technique. The crystal structure of the DbeADCl has been determined and refined to the 1.4 A resolution. The DbeADCl crystals belong to monoclinic space group C121. The DbeADCl molecular structure was characterized and compared with five known haloalkane dehalogenases selected from the Protein Data Bank