摘要
We have used a linker-scan mutation strategy to analyze Pcap99, the proximal promoter of the Autographa californica nuclear polyhedrosis virus (AcMNPV) gene encoding the major capsid protein. A series of recombinant viruses expressing the cat reporter gene under the control of selected mutants of this promoter was constructed. Only mutations that altered bases within a region extending from 8 bp upstream to 6 bp downstream from a TAAG sequence had a significant effect on expression from the late gene promoter. A synthetic promoter consisting of only these 18 bp (Pcapmin) was sufficient to direct late expression. Aside from this small region surrounding the TAAG, no evidence for distinct late activating or repressing sequence elements was obtained. Experiments comparing and combining late and very late gene promoter sequences suggest that late expression is intrinsically determined by the presence and immediate context of a TAAG sequence and that very late expression [as previously shown in Ooi et al. J. Mol. Biol. 210 (1989) 721–736] results from additional modulation of TAAG-dependent expression by downstream promoter elements placed in an appropriate context. A compact combination promoter (95 bp), constructed by fusing Pcapmin to linker-modified very late polyhedrin promoter, directs strong expression at late and very late times post-infection.
摘要译文
我们使用接头扫描突变策略来分析P cap99，它是编码主要衣壳蛋白的苜蓿银纹夜蛾核多角体病毒（AcMNPV）基因的近端启动子。构建了在该启动子的选定突变体控制下表达cat报告基因的一系列重组病毒。只有在TAAG序列下游从上游8bp延伸到下游6bp的区域内改变碱基的突变对晚期基因启动子的表达具有显着影响。仅由这些18bp（P capmin）组成的合成启动子足以指导晚期表达。除了TAAG周围的这个小区域，没有获得明显的晚期激活或抑制序列元件的证据。比较和组合晚期和晚期基因启动子序列的实验表明，晚期表达本质上是由TAAG序列的存在和直接背景决定的，并且是非常晚期的表达[如先前在Ooi等人所述。 J. Mol。生物学。 210（1989）721-736]由置于适当环境中的下游启动子元件对TAAG依赖性表达的额外调节产生。通过将P capmin与接头修饰的非常晚的多角体蛋白启动子融合而构建的紧密组合启动子（95bp）在感染后的晚期和非常晚期指导强烈表达。
Timothy D.Morris;Lois K.Miller;. Mutational analysis of a baculovirus major late promoter[J]. Gene, 1994,140(2): 147-153