Unwinding of duplex DNA from the SV40 origin of replication by T antigen Journal Article
| Authors: | Dodson, M.; Dean, F. B.; Bullock, P.; Echols, H.; Hurwitz, J. |
| Article Title: | Unwinding of duplex DNA from the SV40 origin of replication by T antigen |
| Abstract: | The T antigen specified by SV40 virus is the only viral-encoded protein required for replication of SV40 DNA. T antigen has two activities that appear to be essential for viral DNA replication: specific binding to duplex DNA at the origin of replication and helicase activity that unwinds the two DNA strands. As judged by electron microscopy, DNA unwinding is initiated at the origin of replication and proceeds bidirectionalry. Either linear or circular DNA molecules containing the origin of replication are effective substrates; with dosed circular DNA, a topoisomerase capable of removing positive superhelical turns is required for an efficient reaction. Presence of an origin sequence on duplex DNA and a single-strand DNA-binding protein appear to be the only requirements for T antigen to catalyze unwinding. This reaction mediated by T antigen defines a likely pathway to precise initiation of DNA replication: (i) the sequence-specific binding activity locates the origin sequence, (ii) the duplex DNA is unwound at this she, and (iii) the DNA polymerase and primase begin DNA replication. A similar pathway has been inferred for the localized initiation of DNA replication by bacteriophage λ and by Escherichia coli in which a sequence-specific binding protein locates the origin and directs the DnaB helicase to this site. Observations with the SV40 system indicate that localized initiation of duplex DNA replication may be similar for prokaryotes and eukaryotes. |
| Keywords: | nonhuman; dna replication; animal cell; electron microscopy; microscopy, electron; heredity; tumor antigen; dna; escherichia coli; simian virus 40; plasmids; dna, viral; nucleic acid conformation; antigens, polyomavirus transforming; dna denaturation; support, u.s. gov't, p.h.s.; blood and hemopoietic system |
| Journal Title: | Science |
| Volume: | 238 |
| Issue: | 4829 |
| ISSN: | 0036-8075 |
| Publisher: | American Association for the Advancement of Science |
| Date Published: | 1987-11-13 |
| Start Page: | 964 |
| End Page: | 967 |
| Language: | English |
| DOI: | 10.1126/science.2823389 |
| PUBMED: | 2823389 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | Article -- Erratum issued, see DOI: 10.1126/science.238.4832.1341-e -- Export Date: 5 February 2021 -- Source: Scopus |
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