Role of a repeated hexapeptide motif GIHFAP near C-terminus in assembly, stability, and activity of "HCH dehydrochlorinase LinA".

Ankit S Macwan, Nidhi Srivastava, Saleem Javed, Ashwani Kumar

Index: Appl. Biochem. Biotechnol. 169(4) , 1397-404, (2013)

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Abstract

Enzyme "hexachlorocyclohexane (HCH) dehydrochlorinase LinA" mediates first step of aerobic microbial degradation of a chlorinated insecticide γ-HCH. The archetypal LinA-type1 consists of 156 amino acids that include a directly repeated hexapeptide motif GIHFAP at positions 141-146 and 148-153. Analysis of a series of LinA mutants, containing none, one, two, or three units of this repeated motif revealed that two units, as present in wild-type LinA, are required for its optimal activity and stability. Moreover, the presence of a bend in its secondary structure due to a proline residue that precedes the distal repeated unit contributes to enhanced LinA activity.