Upstream half of adenovirus type 2 enhancer adopts a curved DNA conformation.

The putative enhancer domain of human adenovirus type 2 (Ad2) was revealed to contain a bent DNA structure in the upstream half. By using "deletion analysis", this unusual structure was identified experimentally to span from nucleotide 194 to 269 (figures; nucleotide numbers from the left terminal nucleotide of the viral DNA). This region has almost the same nucleotide sequence as the upstream half of the enhancer and packaging region of Ad5 and, therefore, is thought to contain multiple enhancer elements for transcription and the elements required for packaging of Ad2 DNA. The bent DNA structure of this region was further characterized by analyzing temperature-dependent changes in electrophoretic mobility of the DNA fragments used for bending analysis. Ad2 enhancer provides a good system to investigate the relationship between higher order structure of DNA and transcriptional activation.