Functional Analysis of
Helicase Gene Promoter and Homologous Region 3 Enhancer in Bombyx mori Nuclear
Polyhedrosis Virus
XIAO Qing-Li, ZHANG Zhi-Fang*, YI Yong-Zhu, HE
Jia-Lu, WU Xiang-Fu1
( Key Laboratory of Silkworm Biotechnology, Ministry of Agriculture,
Sericultural Research Institute, Chinese Academy of Agricultural Sciences,
Zhenjiang 212018, China；1Institute of Biochemistry and
Cell Biology, Shanghai Institute for Biological Sciences, the Chinese Academy
of Sciences, Shanghai 200031,
China )
Abstract The
promoter of the helicase gene, including 510 bp upstream of ATG,was cloned and
sequenced, and was found that it had both early and late RNA initiation sites.
The initiation codon ATG was deleted by using point mutation. Luciferase gene,
as a reporter gene, was fused with the promoter region to construct the plsmid
pBmhel510luc. When pBmhel510luc was
transfected into Bm-5 and Sf-21 cell lines, the helicase gene promoter was
recognized by cellular RNA polymerase and transactivated by viral factors.
Baculovirus homologous regions (hrs) act as viral DNA replication start sites,
which also have been shown to alter the rate of transcription for cis-linked
promoters. BmNPV hr3 was cloned into a downstream site of luc
gene, to study the effect of this enhancer on hel510 promoter
activity. The transient expression in transfected insect cell lines and
silkworm larvae indicated that hr3 could enhance the transcriptional
level of hel510 promoter by about 7 000 and 1 000 fold, respectively.
Key words Bombyx mori nuclear
polyhedrosis virus； helicase gene promoter； enhancer；transient expression
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