A cellular Drosophila melanogaster protein with similarity to baculovirus F envelope fusion proteins.
Baculovirus F (fusion) proteins are found in the envelopes of budded virions. Recently a Drosophila melanogaster gene (CG4715) that encodes a protein with sequence similarity to baculovirus F proteins was discovered. To examine similarities and differences with baculovirus F proteins, we cloned the D. melanogaster cellular F (Dm-cF) protein gene and analyzed Dm-cF expression and localization. The predicted Dm-cF protein sequence lacks a furin cleavage site, and transiently expressed Dm-cF showed no protein cleavage and no detectable membrane fusion activity. In cell localization studies, transiently expressed Dm-cF was localized to intracellular organelles in D. melanogaster S2 cells, unlike baculovirus F proteins, which localize to cellular plasma membranes. Using reverse transcriptase PCR and Western blot analysis to examine Dm-cF expression in animals, we detected Dm-cF expression in both larval and adult D. melanogaster cells. However, Dm-cF expression was detected only in third instar larvae and adults, suggesting that Dm-cF expression may be developmentally regulated. We also identified genes related to Dm-cF in the genomes of two other Drosophila species, Drosophila yakuba and Drosophila pseudoobscura, and the mosquito Anopheles gambiae. These observations suggest that f genes may be present in the genomes of many insects. Conservation within and between 22 baculovirus and 4 insect F proteins was examined in detail. These studies demonstrate that Dm-cF is expressed in D. melanogaster and suggest that if baculovirus f genes are derived from a host cellular f gene, the function appears to have changed substantially upon adaptation to the baculovirus infection cycle.
Lung
Oliver
O
Boyce Thompson Institute, Cornell University, Tower Road, Ithaca, NY 14853, USA.
Blissard
Gary W
GW
D000595:Amino Acid Sequence; D000818:Animals; D016367:Baculoviridae / Q000235:genetics*; D001483:Base Sequence; D017124:Conserved Sequence; D017931:DNA Primers; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000254:growth & development; D016679:Genome, Viral; D007814:Larva; D007915:Lepidoptera / Q000821:virology; D008561:Membrane Fusion; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014760:Viral Fusion Proteins / Q000737:chemistry / Q000235:genetics*
D017931:DNA Primers; D029721:Drosophila Proteins; D014760:Viral Fusion Proteins