E2F from adenovirus-infected cells binds cooperatively to DNA containing two properly oriented and spaced recognition sites.
E2F is a sequence-specific DNA-binding factor which binds to sites that occur in pairs upstream of the adenovirus E1A and E2 early transcriptional start sites. Substantial quantities of E2F activity were found in uninfected-cell extracts, and there was a modest increase in E2F activity during an adenovirus type 5 (Ad5) infection. In uninfected cells, E2F was found to exist in multiple forms that could be separated chromatographically. Extracts prepared at 24 h after Ad5 infection contained a new form of E2F. This infection-specific form may have been a modified version of one of the forms present in uninfected cells. The infection-specific E2F was shown to bind cooperatively to a pair of E2F sites found upstream of the Ad2 early region 2 mRNA cap site. This binding was sensitive to the spacing between the sites and their relative orientation. In contrast, E2F binding in uninfected-cell extracts was unaffected by changes in orientation and spacing, consistent with very low cooperativity or independent binding.
Hardy
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Howard Hughes Medical Institute, Department of Biology, Princeton University, New Jersey 08540.
Shenk
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D017456:Adenovirus Early Proteins; D000260:Adenoviruses, Human / Q000235:genetics / Q000378:metabolism*; D000494:Allosteric Regulation; D001483:Base Sequence; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009856:Oncogene Proteins, Viral / Q000302:isolation & purification / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid; D014466:Ultraviolet Rays
D017456:Adenovirus Early Proteins; D015342:DNA Probes; D004268:DNA-Binding Proteins; D009856:Oncogene Proteins, Viral