Tuesday, December 11, 2001 -

Sequence analysis of a putative DNA helicase and four peptides encoded by ORFs of the Diachasmimorpha longicaudata entomopoxvirus (DlEPV)

Dufton M. Mwaengo and Pauline O. Lawrence. University of Florida, Department of Entomology and Nematology, P.O. Box 110620, 970 Natural Area Drive, Gainesville, FL

DlEPV is a symbiotic entomopoxvirus (EPV) of the parasitic wasp Diachasmimorpha longicaudata(Dl). It has a double stranded DNA genome of 250-300 kb and is >60% A-T rich. We describe five DlEPV open reading frames (ORFs) within the first 2.87 kb of the 5 region of clone #35 (RI-35) from a DlEPV EcoRI genomic library. Our goal was to identify unique motifs and compare them with others in the database, particularly those of poxviruses, using Sequencher, PROSITE, and SwissPROT. RI-35-I encodes a putative nuclear peptide of 113 aa, contains a late promoter (TAAATG) and an early transcription stop sequence (TTTTTCT) three nucleotides downstream of the stop codon, and is likely an early/late gene. RI-35-2 is a late gene that presumably encodes a 117 aa cytoplasmic peptide and contains a leucine zipper-like sequence that is predicted to bind DNA, and is probably a transcription factor that regulates viral gene expression. RI-35-3 is a presumed DNA helicase gene whose protein of 480 aa is highly homologous to those of Melanoplus sanguinipesEPV (72%), Amsacta mooreiEPV (72%) and vaccinia virus (69%). DNA helicases unwind the DNA helix during replication and transcription. The DlEPV-encoded enzyme contains six conserved motifs that characterize helicases and is likely a member of the DEXH DNA and RNA helicases. Like its homologs, the RI-35-3 protein has a predicted cytoplasmic location and is probably an intermediate/late gene. RI-35-4 and 5 encode 81 and 106 aa respectively, and are predicted to be cytoplasmic proteins expressed during the intermediate phase of viral morphogenesis. Our results provide additional evidence that DlEPV is a member of the Entomopoxvirinae and is the first symbiotic EPV described to date. Support from the National Science Foundation grants, IBN 9514583 and 9986076 to POL is gratefully acknowledged.

Species 1: Hymenoptera Braconidae Diachasmimorpha longicaudata (parasitic wasp)
Species 2: Poxviridae Diachasmimorpha longicaudata (entomopoxvirus)
Species 3: Diptera Tephritidae Anastrepha suspensa (Caribbean fruit fly)
Keywords: symbiotic virus, DNA helicase

The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA