Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-28258
Nucleic Acids Res 1987 Feb 25;154:1579-94.
Show Gene links Show Anatomy links

pBR322 DNA inhibits simian virus 40 gene expression in Xenopus laevis oocytes.

Michaeli T , Prives C .


Abstract
SV40 DNA form I is expressed efficiently after its injection into the nuclei of Xenopus laevis oocytes, resulting in the synthesis of RNA and protein products of both viral late and early transcription units. However it was observed that injection of SV40 genes cloned into pBR322 or related plasmids yielded vastly reduced quantities of viral DNA and proteins. If SV40 DNA was cleaved from the plasmid, and then recircularized prior to microinjection, viral expression was regained. The inhibition by plasmid DNA was not confined to an effect in cis because coinjection of circular pBR322 DNA along with SV40 DNA, as separate entities, also blocked viral RNA and protein synthesis. As circular but not linear pBR322 DNA was actively transcribed by polymerase II in oocytes, even in the presence of SV40 DNA, it is likely that pBR322 competes for transcription factors required for viral gene expression. Injection of pBR322 as early as two hours after injection of SV40 DNA into the oocyte nucleus did not inhibit SV40 RNA synthesis, indicating that once initiated, SV40 transcription is stable and insensitive to the competition by plasmid DNA. A plasmid vector was developed that allows expression of SV40 DNA in Xenopus laevis oocytes.

PubMed ID: 3029720
PMC ID: PMC340568
Article link: Nucleic Acids Res
Grant support: [+]


References [+] :
Asselbergs, Analysis of expression of adenovirus DNA (fragments) by microinjection in Xenopus oocytes. Independent synthesis of minor early region 2 proteins. 1983, Pubmed, Xenbase