Novel LinA Type 3 δ-Hexachlorocyclohexane Dehydrochlorinase
Shrivastava, N., Prokop, Z., Kumar, A.
APPLIED AND ENVIRONMENTAL MICROBIOLOGY 81: 7553-7559 (2015)
LinA is first enzyme of the microbial degradation pathway of a chlorinated insecticide hexachlorocyclohexane (HCH), and mediates the dehydrochlorination of α-, γ- and δ-HCH. Its two variants, LinA-type 1 and LinA-type 2, which differ at 10 out of 156 amino acid residues, have been described. Their activities for the metabolism of different HCH-isomers differ considerably, but overall are high for γ-HCH, moderate for α-HCH, low for δ-HCH and none for β-HCH. Here, we describe the characterization of a new variant of this enzyme, LinA-type 3, whose gene was identified from the metagenome of an HCH-contaminated soil. Its deduced primary structure in 1-147 amino acid residues region of the protein exhibits 17 and 12 differences from LinA-type 1 and LinA-type 2, respectively. In addition, the residues GIHFAPS, present at the location 148-154 in both LinA-type 1 and LinA-type 2, are deleted in LinA-type 3.The activity of LinA-type 3 for the metabolism of δ-HCH is several orders of magnitude higher than LinA-type 1 or LinA-type 2, and can be useful for the improved metabolism of δ-HCH.