Expression and functional validation of Bombyx mori nucleopolyhedrovirus ORF29, a conserved Nudix motif protein

Abstract

Our previous study showed that Bombyx mori nucleopolyhedrovirus (BmNPnpV) orf29 encodes a 26 kDa protein expressed in the early stage of infection cycle. BmNPnpV ORF29, contains a conserved motif of Nnudix (nucleotide diphosphate X) superfamily. Iit has the highest homology with ADPp-ribose pyrophosphatase (ADPpRase), a subfamily of pyrophosphatase. Iin this work, we purified the recombinant BmNPnpV ORF29 in Escherichia coli by metal chelating affinity chromatography. The amino acid sequence of recombinant protein was confirmed by mass spectroscopic analysis and found that the purified protein could be able to catalyze the breakdown of ADPp-ribose to AMPp and ribose 5-phosphate, with K m and K cat values of 182 μmol/l and 5.3 s -1 respectively. The optimal activity was at alkaline pH (8.5) with Mg 2+ (0.5-mmol/l) ions as the cofactor.