Nucleotide Sequence Analysis of the HcNPV Cysteine Protease Gene

The cysteine protease (CP) gene of Hyphantria cunea nuclear polyhedrosis virus (HcNPV) has been located at the Hind III--3.5 kb fragment. The nucleotide sequence has been determined. The results indicated that its open reading frame of 975 nt encoded the protein of 324 amino acids. The baculovirus late gene promoter TAAG motif was identified at -24 nt upstream from the start codon ATG; The typical poly (A) signal sequence AATAAA was detected at 33 nt downstream from the stop codon TAA. The HcNPV CP exhibited 81%, 76% and 76% homology at the nucleotide level, and 85%, 78%, 76% homology at the amino acid level to that of CfNPV (Choristoneura fumiferana nuclear polyhedrosis virus), AcNPV (Autographa californica nuclear polyhedrosis virus) and BmNPV (Bombyx mori nuclear polyhedrosis virus), respectively. HcNPV CP was a memeber of the papain superfamily and showed high homology to other cysteine protease, particularly, to those from Trypanosoma brucei and Dictyostelium discoideumwith 31.8%, 34.5% identity at the amino acid level, respectively. Of 36 residues conserved among cathepsins B, H, L and S and papain, 32 were identical in HcNPV CP. The ERFNIN interspersed amino acid motif was found within the propeptide region of the HcNPV CP. The Gly-Cys-Asn-Gly-Gly motif conserved among all cysteine protease was also detected in HcNPV CP.