Haloalkane dehalogenases catalyse the hydrolysis of halogenated hydrocarbons to alcohols. Because toxic haloalkanes are common waste products and contaminants of industrial sites, haloalkane dehalogenases may prove to be a useful tool in facilitating the breakdown of these harmful chemicals. Crystal structures for seven haloalkane dehalogenases currently exist, which represents a small fraction of sequence space for this family. Using phylogenetic approaches, we selected a distant member of the family from Mycobacterium rhodesiae JS60 and solved the structure of the recombinant protein to a resolution of 2.4 Å. This size of the active site cavity and putative access tunnels suggest that this enzyme should preferentially target short linear haloalkanes. We now seek to determine the substrate specificity of this enzyme to gain a better understanding of the structure-specificity relationships of haloalkane dehalogenases. This should help inform the design of specific and efficient enzymes to target distinct classes of haloalkanes.

Furthermore, we have constructed an ancestral enzyme based on 126 genome-annotated haloalkane dehalogenases using maximum likelihood and Bayesian methods. This enzyme has residual activity and can potentially serve as a template for directed evolution towards novel activity, which can ultimately be applied to the bioremediation of problem haloalkanes.