Adenovirus E3-early promoter: sequences required for activation by E1A.

To identify sequences within the adenovirus-5 E3 promoter necessary for E1A trans-activation, a series of promoter deletion mutants were constructed and analysed. A region between positions -82 and -105 was shown to be critical both for E1A induced expression as well as uninduced expression. The importance of this region was confirmed by constructing hybrid promoters consisting of E3 and Herpes simplex virus thymidine kinase sequences. The E1A insensitive tk promoter could be converted to an E1A sensitive promoter by replacing sequences upstream of position -79 with the corresponding region of the E3 promoter. This critical region of the E3 promoter contains a sequence 5' AGATGACTA3' which is also present in important upstream regions of the E2A and E4 promoters.