Ecdysone response element in a baculovirus immediate-early gene, ie1, promoter.
A computer-assisted analysis identified tentative target sequences for regulatory proteins including ecdysone-inducible factors such as BmFTZ-F1 and Broad-Complex Z4 (BR-C Z4) in the ie1 promoter of BmNPV. A transient expression experiment using BmN cells and a series of truncated ie1 promoter constructs demonstrated that the activity of the ie1 promoter responded to alpha-ecdysone and 20-hydroxyecdysone, which required a tridecameric nucleotide stretch (ie1EcRE, 5'-GTGTTATCGACCT-3') homologous to the ecdysone response element reported for Drosophila (DmEcRE). RT-PCR demonstrated the expression of BmEcR and BmUSP, which are required as ecdysone-specific activators for EcRE-mediated activation, in BmN cells. Furthermore, the ie1 EcRE-mediated response was confirmed by using a recombinant BmNPV possessing a luciferase gene under the control of the ie1 promoter with or without ie1 EcRE. This is the first report of an ecdysone response element in a baculoviral gene promoter. These results also suggested that the regulation of the ie1 by ecdysone may militate viral replication at least under certain conditions during natural infections in vivo.
Silk-Materials Research Unit, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan.
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Kojima
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Oritani
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Nakatsukasa
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Asano
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Sahara
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Bando
D000818:Animals; D019677:Artificial Gene Fusion; D016367:Baculoviridae / Q000235:genetics* / Q000502:physiology; D012831:Bombyx; D002460:Cell Line; D004440:Ecdysone / Q000378:metabolism*; D004441:Ecdysterone / Q000378:metabolism; D005786:Gene Expression Regulation; D017781:Genes, Immediate-Early; D017930:Genes, Reporter; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D011401:Promoter Regions, Genetic; D020218:Response Elements / Q000235:genetics*
D004440:Ecdysone; D004441:Ecdysterone; D008156:Luciferases