Localisation of identical organophosphorus pesticide degrading (opd) genes on genetically dissimilar indigenous plasmids of soil bacteria: PCR amplification, cloning and sequencing of opd gene from Flavobacterium balustinum.

Plasmid borne organophosphorus pesticide degrading (opd) gene of Flavobacterium balustinum has been amplified using polymerase chain reaction (PCR) and the resulting PCR product (1.25 Kb) was cloned in pUC18. Further, a detailed restriction map was determined to PCR product and subcloned as overlapping restriction fragments. The nucleotide sequence was determined for all subclones to obtain complete sequence of PCR amplified fragment. The sequence showed 98% similarity to opd genes cloned from other soil bacteria isolated from diversified geographical regions. The protein sequence predicted from the nucleotide sequence was almost identical to parathion hydrolase, a triesterase involved in hydrolysis of triester bond found in variety of op-pesticides. The signal sequence of parathion hydrolase contained recently discovered twin arginine transport (tat) motif. It appears that tat motif plays a critical role in membrane targeting of parathion hydrolase.