Submitted to: Insect Molecular Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/27/2007
Publication Date: 8/22/2007
Citation: Shirk, P.D., Bossin, H., Furlong, R.B., Gillett, J. 2007. Regulation of Junonia coenia densovirus P9 promotor expression. Insect Molecular Biology. 16:623-633. Interpretive Summary: Insect pest damage of crops is a continually increasing problem in agriculture due to the loss of most insecticides because of acquired resistance or environmental hazard. Agribusiness is left with fewer options for pest control. Scientists at the USDA ARS, Center from Medical, Agricultural and Veterinary Entomology, Gainesville, FL, have identified a portion of a virus genome that is essential for promoting gene activity. This "enhancer" activates and is central to the creation of genetic materials and their products. The enhancer functioned in flies and moths and, because it accelerates the production of chemicals useful in pest control, it provides an important tool in enhancer applied molecular genetics.
Technical Abstract: Transcriptional activity of the P9 promoter in the Junonia coenia densovirus (JcDNV) depends on a 685 bp enhancer located in a 3’ sequence of the NS gene. Utilizing the somatic transformation activity of a modified JcDNV vector, JDR, in Drosophila melanogaster and Plodia interpunctella, the viral sequences were subjected to deletional analysis to assess the affect of various regions on P9 promoter activity. Previously, removal of most of the NS gene and the 3’ inverted terminal repeat (ITR) had not affected P9 driven expression. Removal of a 685 bp fragment from the 3’ end of the NS gene eliminated expression from the P9 promoter. When secondary reporter cassettes that were transcriptionally independent of JcDNV sequences were included in a 685 bp deleted JDR vector, expression of the independent cassettes persisted throughout larval development confirming that somatic transformation of the deleted JDR vector occurred and that transformation was not dependent on the 685 bp fragment. P9 activity was restored by reinsertion of the 685 bp fragment and was functionally orientation independent. P9 promoter driven expression was stimulated by inclusion of the heterologous baculovirus hr5 enhancer. Binding sites corresponding to the polycomb/YY1, Sox and GATA-3 transcriptional factors were identified within the 685 bp fragment and within the inverted terminal repeats by comparison with known binding sites. These findings identify an enhancer sequence internal to J. coenia (JcES) common to closely related densovirus genomes that is critical for supporting transcriptional activity from the JcDNV P9 promoter.