Abstract:
:The polyomavirus enhancer is located adjacent to the origin of DNA replication and the transcriptional promoters. It has a cis-acting essential function in the initiation of both viral DNA synthesis and early transcription. The enhancer is activated by the binding of protein factors to specific sites in DNA. Mutants with deletions of the A- or the B-segment of the enhancer were constructed. In mouse 3T6 cells, the transcription of the viral early region was significantly decreased by deletion of the A-segment, but not by deletion of the B-segment. In contrast, the two deletions had a similar, moderately negative effect on viral DNA synthesis. However, the presence of DNA with a wild-type enhancer in doubly transfected cells resulted in very strong interference with the replication, but not with the transcription, of deletion mutant DNA. DNA of the deletion mutants were subjected to site-directed mutagenesis of the remaining enhancer segment. Three non-viable mutants were isolated. All three had base-pair changes in the A-segment affecting immediately adjacent binding sites of cellular protein factors. The mutants had lost the enhancer activity on the early promoter, but only one of them with multiple base substitutions had lost the capacity of DNA replication. Together, the results suggest that different aspects of enhancer function determine the activity in initiation of transcription and replication.
journal_name
J Mol Bioljournal_title
Journal of molecular biologyauthors
Nilsson M,Osterlund M,Magnusson Gdoi
10.1016/0022-2836(91)90690-8subject
Has Abstractpub_date
1991-04-05 00:00:00pages
479-83issue
3eissn
0022-2836issn
1089-8638pii
0022-2836(91)90690-8journal_volume
218pub_type
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