Abstract:

【Objective】 The non-structural protein 2 (NS2) gene of Bombyx mori densovirus Zhenjiang strain (BmDNV-Z) was cloned and expressed so as to test the biological activities of the expressed recombinant protein. 【Method】 The gene of the non-structure protein 2 (NS2) was cloned by PCR from the genome of Bombyx mori densovirus Zhenjiang strain, inserted into prokaryotic expression vector pET28a to construct recombinant plasmid pET28a-NS2 and then expressed in bacteria E. coli BL21 (DE3). The expressed recombinant protein was identified by SDS-PAGE and Western blot analysis. Then the recombinant protein was purified by Ni-NTA column, renatured and tested for enzyme activities. 【Result】 The gene of BmDNV-Z NS2 was cloned and successfully expressed in bacteria E. coli, and the expressed target protein NS2 was purified by Ni–NTA affinity chromatography. The purified NS2 protein exhibited a helicase activity unwinding double-stranded DNA substrates into single-strand primers, and higher unwinding activity to polarity substrate. At the meantime, the purified NS2 protein possessed a ATPase activity and its enzyme activity was 0.276 μmol?μg-1?h-1 in this study. 【Conclusion】 The non-structure protein which encoded by the gene of BmDNV-Z NS2 possesses the biological activities of helicase and ATPase, and meanwhile the helicase prefers to polarity substrates. Based on these results, it is speculated that the gene of BmDNV-Z NS2 plays an important role in the viral DNA replication.

Key words: Bombyx mori, densovirus, non-structure protein, expression, activity