Timing of ultraviolet light induced mutagenesis in simian virus 40 relative to viral DNA replication in monkey cells

1985 ◽  
Vol 201 (3) ◽  
pp. 421-425 ◽  
Author(s):  
Jan J. Cornelis ◽  
Jean Rommelaere
1990 ◽  
Vol 10 (9) ◽  
pp. 4996-5001 ◽  
Author(s):  
R Rochford ◽  
C T Davis ◽  
K K Yoshimoto ◽  
L P Villarreal

The cell-specific regulation of DNA replication has important implications for the molecular strategy of cellular gene control. Mouse polyomavirus (Py) DNA replication is examined as a model of cell-specific replication control. Using an FM3A-derived mouse cell line which expresses early viral proteins (FOP cells), we determined the minimal sequence requirements for viral DNA replication. FOP cells were observed to have much simpler enhancer requirements than 3T6 and many other cells and did not need a B enhancer for high levels of DNA replication. Using these cells, we show that the individual or tandem binding sites for several unrelated trans-acting factors which are generally subfunctional as transcriptional enhancers (simian virus 40 A core, TGTGGAATG; EBP20, TGTGGTTTT; PEA1 [an AP-1 analog], GTGACTAA; PEA2, GACCGCAG; and PEA3, AGGAAG) stimulated low levels of Py DNA replication. The ordered dimeric combination of PEA3 and PEA1 factor-binding sites, however, acted synergistically to stimulate viral DNA replication to high wild-type levels. This is in contrast to prior results in which much larger enhancer sequences were necessary for high-level viral DNA replication. PEA3/PEA1-stimulated DNA replication showed a distance and orientation independence relative to the origin, which disagrees with some but not other prior analyses of enhancer-dependent DNA replication. It therefore appears that trans-acting factor-binding sites (enhansons) can generally activate DNA replication and that the AP-1 family of sites may act synergistically with other associated trans-acting factors to strongly affect Py DNA replication in specific cells.


1990 ◽  
Vol 64 (12) ◽  
pp. 6234-6245 ◽  
Author(s):  
I Reynisdóttir ◽  
D R O'Reilly ◽  
L K Miller ◽  
C Prives

1984 ◽  
Vol 4 (9) ◽  
pp. 1915-1928 ◽  
Author(s):  
A R Buchman ◽  
P Berg

As part of our efforts to create multifunctional vectors for the transduction of animal cells, a set of simian virus 40 recombinants were constructed which contain an inverted duplication of the region including the origin of viral DNA replication (ori) and the early-region promoter. The unusual aspects of the structure of these recombinant genomes revealed several unexpected features of their function. In particular, transcription from the early-region promoters on these recombinants occurred primarily after the start of DNA replication, and, in that sense, these promoters behaved as if they were late-region promoters. This behavior results from the fact that these genomes contain multiple ori segments, and, therefore, they replicate earlier and faster than wild-type virus DNA, thereby causing a precocious shift in the initiation of early-region transcription from sites downstream of ori to sites located upstream of ori. The abnormal expression from multiple ori genomes is consistent with our present notions regarding the replication-dependent shift in early-region transcriptional start sites (Buchman et al., Mol. Cell. Biol. 4:1900-1914). Since our experiments demonstrate that RNAs initiated upstream of ori contribute to T-antigen formation late in infection, we suggest that the shift in early-region transcription starts modulates large T-antigen production in concert with viral DNA replication.


1990 ◽  
Vol 10 (9) ◽  
pp. 4996-5001 ◽  
Author(s):  
R Rochford ◽  
C T Davis ◽  
K K Yoshimoto ◽  
L P Villarreal

The cell-specific regulation of DNA replication has important implications for the molecular strategy of cellular gene control. Mouse polyomavirus (Py) DNA replication is examined as a model of cell-specific replication control. Using an FM3A-derived mouse cell line which expresses early viral proteins (FOP cells), we determined the minimal sequence requirements for viral DNA replication. FOP cells were observed to have much simpler enhancer requirements than 3T6 and many other cells and did not need a B enhancer for high levels of DNA replication. Using these cells, we show that the individual or tandem binding sites for several unrelated trans-acting factors which are generally subfunctional as transcriptional enhancers (simian virus 40 A core, TGTGGAATG; EBP20, TGTGGTTTT; PEA1 [an AP-1 analog], GTGACTAA; PEA2, GACCGCAG; and PEA3, AGGAAG) stimulated low levels of Py DNA replication. The ordered dimeric combination of PEA3 and PEA1 factor-binding sites, however, acted synergistically to stimulate viral DNA replication to high wild-type levels. This is in contrast to prior results in which much larger enhancer sequences were necessary for high-level viral DNA replication. PEA3/PEA1-stimulated DNA replication showed a distance and orientation independence relative to the origin, which disagrees with some but not other prior analyses of enhancer-dependent DNA replication. It therefore appears that trans-acting factor-binding sites (enhansons) can generally activate DNA replication and that the AP-1 family of sites may act synergistically with other associated trans-acting factors to strongly affect Py DNA replication in specific cells.


1999 ◽  
Vol 73 (2) ◽  
pp. 1099-1107 ◽  
Author(s):  
Utz Herbig ◽  
Klaus Weisshart ◽  
Poonam Taneja ◽  
Ellen Fanning

ABSTRACT Simian virus 40 (SV40) large tumor (T) antigen is the major regulatory protein that directs the course of viral infection, primarily by interacting with host cell proteins and modulating their functions. Initiation of viral DNA replication requires specific interactions of T antigen bound to the viral origin of DNA replication with cellular replication proteins. Transcription factors are thought to stimulate initiation of viral DNA replication, but the mechanism of stimulation is poorly understood. Since the transcription factor TATA-binding protein (TBP) binds to sequences within the origin of replication and interacts specifically with T antigen, we examined whether TBP complexes stimulate SV40 DNA replication in vitro. On the contrary, we found that depletion of TBP complexes from human cell extracts increased their ability to support viral DNA replication, and readdition of TBP complexes to the depleted extracts diminished their activity. We have mapped the sites of interaction between the proteins to residues 181 to 205 of T antigen and 184 to 220 of TBP. Titration of fusion proteins containing either of these peptides into undepleted cell extracts stimulated their replication activity, suggesting that they prevented the T antigen-TBP interaction that interfered with replication activity. TBP complexes also interfered with origin DNA unwinding by purified T antigen, and addition of either the T antigen or the TBP fusion peptide relieved the inhibition. These results suggest that TBP complexes associate with a T-antigen surface that is also required for origin DNA unwinding and viral DNA replication. We speculate that competition among cellular proteins for T antigen may play a role in regulating the course of viral infection.


1979 ◽  
Vol 29 (3) ◽  
pp. 983-989 ◽  
Author(s):  
E H Birkenmeier ◽  
N Chiu ◽  
M F Radonovich ◽  
E May ◽  
N P Salzman

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