Mapping of ORF121, a Factor That Activates Baculovirus Early Gene Expression

• Published in: Virology (New York, N.Y.) Vol. 244; no. 2; pp. 495 - 503
• Main Authors: Gong, Min, Jin, Jianping, Guarino, Linda A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 10-05-1998
• Subjects: Amino Acid Sequence; Animals; AUTOGRAPHA CALIFORNICA; AUTOGRAPHA CALIFORNICA NUCLEAR POLYHEDROSIS VIRUS; Base Sequence; Cells, Cultured; Chloramphenicol O-Acetyltransferase - genetics; Chromosome Mapping; DNA, Viral - genetics; DNA-Binding Proteins - genetics; Gene Expression; Genes, Reporter; Genes, Viral; Immediate-Early Proteins - genetics; MOLECULAR SEQUENCE DATA; NUCLEAR POLYHEDROSIS VIRUS; Nucleopolyhedrovirus - genetics; Nucleopolyhedrovirus - metabolism; Open Reading Frames; Phosphoproteins - genetics; Plasmids - genetics; Recombination, Genetic; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Viral - genetics; RNA, Viral - metabolism; Trans-Activators - genetics; VIRUS POLIEDROSIS NUCLEAR; VIRUS POLYEDROSE NUCLEAIRE
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1006/viro.1998.9116

The protein product of the39kgene ofAutographa californicanuclear polyhedrosis virus is thought to be important for viral replication because of its association with the virogenic stroma and its role in activation of late gene expression. Transient expression assays showed that addition of a DNA fragment encoding a 58-amino-acid polypeptide increased expression of a39kreporter plasmid. This stimulation was dependent on cotransfection of a plasmid encoding IE1. Cotransfection of this gene,orf121,also stimulatedie1expression, and the activation ofie1was even more dramatic in the presence of IE1. These data suggested that ORF121 stimulated39kexpression by upregulation of IE1 expression. Activation of39kby ORF121 and the viral transcription factor IE2 was additive, while activation by ORF121 and the apoptotic suppressor P35 was synergistic. Cotransfection of p39cat and pIE1 with plasmids encoding ORF121, IE2, and P35 stimulated 39cat expression more than 100-fold compared to cells transfected with only p39cat and pIE1. These data suggest that IE2 and ORF121 work by similar mechanisms and indirectly activate p39cat by increasing IE1 expression, while P35 increases 39cat expression by a different mechanism.