Cloning and expression nahC gene encoding 1,2-dihydroxynaphthalene dioxygenase of Paenibacillus naphthalenovorans 4B1

Abstract

Polycyclic aromatic hydrocarbon compounds used in many industries have caused environmental pollutions and left consequences to human health. Naphthalene, the simplest polycyclic aromatic hydrocarbon, is widely used as a model compound for biodegradation studies in bacteria. The 1,2-dihydroxynaphthalene dioxygenase, a benzene ring-cleavage enzyme, converts intermediate compounds in the naphthalene degradation pathway into less toxic compounds. In this study, the nahC gene encoding 1,2-dihydroxynaphthalene dioxygenase from the moderate thermophilic Paenibacillus naphthalenovorans strain 4B1 was cloned into pGEM-T Easy vector. Subsequently, the gene after confirming the correct DNA sequence was ligated into pCold^TM II expression vector and transformed to Escherichia coli BL21. The SDS-PAGE results showed that the nahC gene was successfully expressed in E. coli BL21 with 0.5 mM IPTG. The molecular weight of resulting recombinant enzyme was approximately 35 kDa. These results are the basis for enzyme purification and characterization.