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Important amino acid residues of hexachlorocyclohexane dehydrochlorinases (LinA) for enantioselective transformation of hexachlorocyclohexane isomers.

  • Shrivastava N Academy of Scientific and Innovative Research, New Delhi, India.
  • Macwan AS Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
  • Kohler HE Department of Environmental Microbiology, Swiss Federal Institute for Aquatic Science and Technology (Eawag), Dübendorf, Switzerland. hanspeter.kohler@eawag.ch.
  • Kumar A Academy of Scientific and Innovative Research, New Delhi, India.
  • 2017-03-03
Published in:
  • Biodegradation. - 2017
Enantioselectivity
HCH dehydrochlorinase LinA
α-HCH enantiomers
Amino Acids
Biodegradation, Environmental
Chromatography, Gas
Hexachlorocyclohexane
Lyases
Mutant Proteins
Mutation
Stereoisomerism
Structure-Activity Relationship
English LinA-type1 and LinA-type2 are two well-characterized variants of the enzyme 'hexachlorocyclohexane (HCH)-dehydrochlorinase'. They differ from each other at ten amino acid positions and exhibit differing enantioselectivity for the transformation of the (-) and (+) enantiomers of α-HCH. Amino acids responsible for this enantioselectivity, however, are not known. An in silico docking analysis identified four amino acids (K20, L96, A131, and T133) in LinA-type1 that could be involved in selective binding of the substrates. Experimental studies with constructed mutant enzymes revealed that a combined presence of three amino acid changes in LinA-type1, i.e. K20Q, L96C, and A131G, caused a reversal in its preference from the (-) to the (+) enantiomer of α-HCH. This preference was enhanced by the additional amino acid change T133 M. Presence of these four changes also caused the reversal of enantioselectivity of LinA-type1 for δ-HCH, and β-, γ-, and δ-pentachlorocyclohexens. Thus, the residues K20, L96, A131, and T133 in LinA-type1 and the residues Q20, C96, G131, and M133 in LinA-type 2 appear to be important determinants for the enantioselectivity of LinA enzymes.
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  • English
Open access status
hybrid
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https://sonar.ch/global/documents/156090
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