Recently replicated simian virus 40 DNA is a preferential template for transcription and replication

The relationship between adenovirus replication and late transcription has been investigated using viral replication and transcription complexes isolated from infected HeLa cell nuclei. These two types of complexes extracted from adenovirus type 2-infected cell nuclei did not sediment at the same rate on sucrose gradients. Viral replicative intermediates were quantitatively precipitated by immunoglobulins raised against purified 72,000-dalton DNA-binding protein, whereas viral transcription complexes remained in the supernatant. These results show that late transcription does not occur on active replication complexes or on 72,000-dalton DNA-binding protein-containing replicative intermediates inactive in DNA synthesis. Additional evidence is presented indicating that it is very unlikely that replicative intermediates lacking the 72,000-dalton DNA-binding protein could be the template for late transcription.

Section: Resultsmentioning

confidence: 76%

Adenovirus DNA template for late transcription is not a replicative intermediate

Brison¹,

Kédinger²,

Chambon³

1979

“…A role for maturation proteins was postulated by Roman and Dulbecco (22) and Roman (21). Similarly, Garber et al (8) and Baumgartner et al (1) compared their determinations on the rate of encapsidation of DNA with the published data on the kinetics of reentry of DNA into replication (9,21,22), and postulated an association between the two pathways.…”

mentioning

confidence: 97%

Cessation of reentry of simian virus 40 DNA into replication and its simultaneous appearance in nucleoprotein complexes of the maturation pathway

Wang¹,

Roman²

1981

Newly synthesized SV40 DNA is used as a template for further DNA synthesis (reenters replication) or as a substrate in the assembly of virions (maturation pathway). The time courses of reentry into replication and progression along the maturation pathway were both determined on identical samples. DNA, synthesized during a 20-min pulse, reentered replication over a period of several hours and then was removed from the pool of molecules available for replication. The cessation of reentry coincided with the maturation of this DNA from the chromatin form to previrion and virion forms. More reentry and less maturation was observed at 24 h postinfection than at 42 h postinfection. The data are consistent with the hypothesis that the factor(s) responsible for cessation of reentry is also responsible for initiation of the maturation pathway.

“…More than 90% of the [3H]DNA from both irradiated and unirradiated cells was covalently closed; thus, degradation of the pulse label cannot be the cause of the inhibition. Since a fraction of the prelabeled DNA is used as a template for further DNA synthesis (12,24) and pyrimidine dimers appear to block replication forks (4, 5), we asked whether the [3H]DNA was accumulating as parental strands of replicative intermediates whose completion was inhibited. By T = 2 h, the fraction of label from the NPC-I pool which behaved as replicative intermediates on benzoylated-napthoylated DEAE (BND)-cellulose columns (15) was 5 to 6% in unirradiated cultures and 13 to 19% in the cultures irradiated with 108 J m-2; irradiation of purified form I DNA with this fluence increased the fraction retarded on BND-cellulose from…”

Section: Resultsmentioning

confidence: 99%

Ultraviolet irradiation inhibits encapsidation of simian virus 40 chromatin

Roman

Edenberg²

1981

During normal maturation and majority of pulse-labeled simian virus 40 DNA progresses from chromatin to previrions and virions within 5 h. UV light inhibits this progression. In heavily irradiated cultures (108 J m-2) most of the simian virus 40 DNA synthesized immediately before irradiation remains as chromatin for at least 5 h. This inhibition of maturation seems to be a result of the inhibition of protein synthesis. The data suggest that the pool of proteins required for maturation is sufficient to convert one-third of the simian virus 40 DNA molecules labeled in a 10-min pulse (at 33 h postinfection) from chromatin to previrions and virions and is exhausted within 1 h.