Purification, crystallization and preliminary crystallographic analysis of DehIVa, a dehalogenase from Burkholderia cepacia MBA4.

DehIVa is one of two dehalogenases produced by the soil- and water-borne bacterium Burkholderia cepacia MBA4. It acts to break down short-chain halogenated aliphatic acids through a nucleophilic attack and subsequent hydrolysis of an enzyme-substrate intermediate to remove the halide ions from L-enantiomers substituted at the C2 position (e.g L-2-monochloropropionic acid). Dehalogenases are an important group of enzymes that are responsible for breaking down a diverse range of halogenated environmental pollutants. The dhlIVa gene coding for DehIVa was expressed in Escherichia coli and the protein was purified and crystallized using the hanging-drop method. Crystals grown in PEG 4000 and ammonium sulfate diffracted to 3.1 A. The crystals had a primitive hexagonal unit cell, with unit-cell parameters a = b = 104.2, c = 135.8 A, alpha = beta = 90, gamma = 120 degrees. Determining this structure will provide valuable insights into the characterization of the catalytic mechanisms of this group of enzymes.