Characterization of the Autographa californica Nucleopolyhedrovirus Ubiquitin Gene Promoter

摘要

Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) encodes an ubiqui-tin protein, which may be involved in virus infection. Functional analysis of the AcMNPV ubiquitin promoter was performed by progressive deletion of sequence or mutation of puta-tive cis-activating motifs in the promoter region. In the presence of viral factors, a transient expression assay demonstrated that the active regions responsive to promoter transcription are mainly located within the range of -595 to –382 bp upstream of ATG. A 196-bp fragment (-383 to –187 bp), consisting of the distal TAAG, CAAT motif and TATA box, could also drive the expression of a reporter gene. Site-directed mutagenesis analyses indicated that mutations of TATA boxes and TAAG motifs reduce the promoter activity remarkably, while CAAT mutations enhance the promoter activity by about 3- or 4-fold as compared to the native promoter. All the results suggested that two continuous promoter regions are involved in the transcription of the ubiquitin gene and the cis-activating motifs corresponding to viral factors are mainly present within the 5' region of the promoter. In addition, CAAT motifs in the promoter region function as negative regulator(s) binding sites.