[Structural and functional study of prokaryotic enhancer-like element VV1 from vaccinia virus]

Enhancer VV1 (about 283 bp) is selected as the target to analyze its structure and function systemically. Stepwise deletion experiment is used to identify the functional domain of VV1 element. The results suggest that the 20 bp at 5' terminal and 20 bp at 3' terminal are important to the activity of VV1, for without either of them its activity decreased greatly. Furthermore, the 30-50 bp at 5' terminal is essential to its activity, without which will lead to complete loss of its activity. By random mutagenesis assay it is found that base mutation can regulate the activity of enhancer VV1 positively or negatively. The more the activities of mutants descend, the more mutations take place. For singlebase mutation, the activities change relatively little, and most of the mutations always occur in the 50 bp at the 5' terminal.