Choristoneura fumiferana Granulovirus p74 Protein, a Highly Conserved Baculoviral Envelope Protein

Abstract

A gene that encodes a homologue to baculoviral p74, an envelope-associated viral structural protein, has been identified and sequenced on the genome of Choristoneura fumiferana granulovirus (ChfuGV). A part of the ChfuGV p74 gene was located on an 8.9 kb BamHI subgenomic fragment using different sets of degenerated primers. These were designed using the results of the protein sequencing of a major 74 kDa structural protein that is associated with the occlusion-derived virus (ODV). The gene has a 1992 nucleotide (nt) open-reading frame (ORF) that encodes a protein with 663 amino acids with a predicted molecular mass of 74,812 Da. Comparative studies revealed the presence of two major conserved regions in the ChfuGV p74 protein. This study also shows that all of the p74 proteins contain two putative transmembrane domains at their C-terminal segments. At the nucleotide sequence level, two late promoter motifs (TAAG and GTAAG) were located upstream of the first ATG of the p74 gene. The gene contained a canonical poly(A) signal, AATAAA, at its 3 non-translated region. A phylogenetic tree for baculoviral p74 was constructed using a maximum parsimony analysis. The phylogenetic estimation demonstrated that ChfuGV p74 is related the closest to those of Cydia pomonella granulovirus (CpGV) and Phthorimaea operculella granulovirus (PhopGV).

Identification, Characterization and Phylogenic Analysis of Conserved Genes within the p74 Gene Region of Choristoneura fumiferana Granulovirus Genome

“…The multiple alignment of the ChfuGV p74 protein with those of the other BVs revealed that several glycine and proline residues were preserved in almost all the baculoviral p74 proteins (Rashidan et al, 2003). Another remarkable aspect of the ChfuGV p74 protein is the existence of an 8 cysteine residue cluster, six of those cysteine residues were shown to be conserved in all of the known p74 homologues (Rashidan et al, 2003).…”

“…The multiple alignment of the ChfuGV p74 protein with those of the other BVs revealed that several glycine and proline residues were preserved in almost all the baculoviral p74 proteins (Rashidan et al, 2003). Another remarkable aspect of the ChfuGV p74 protein is the existence of an 8 cysteine residue cluster, six of those cysteine residues were shown to be conserved in all of the known p74 homologues (Rashidan et al, 2003). The high level of preservation of cysteine, glycine and proline residues in all baculoviral p74 proteins could mean that the p74 protein plays an important role in the life cycle of all baculoviruses and mutations on these preserved residues might ultimately lead to the exclusion of the mutated virus from the evolutionary pathway.…”

“…This paper reports the identification and characterization of the ORFs located within the p74 gene region of the ChfuGV. Gene p74 is a highly conserved baculoviral gene coding an envelope protein, and the complete sequence and characterization of this gene along with its product in the ChfuGV has been reported recently (Rashidan et al, 2003). The ORFs located within the p74 gene region of the ChfuGV are positioned downstream to those within the odvp-6e/odv-e56 gene region.…”

Sequencing and Characterisation of p74 Gene in Two Isolates of Anticarsia Gemmatalis MNPV

“…A membrane anchoring segment in the C-terminal region can be predicted and would be essential for its association with the envelope [16,17]. The other hydrophobicity regions, some of which were predicted in previous studies [15][16][17], could be necessary for correct folding and organisation or may be also part of transmembrane topology. In contrast, the amino terminus of P74 is principally hydrophilic and could be exposed outside of PDV envelopes.…”

“…The best characterised very late gene is polyhedrin, which encodes the major protein of the occlusion body matrix, makes up protective enclosure that contributes to the survival of the occluded virus in the environment. Other important very late genes are p10 and p74 [11][12][13][14][15].…”