Preformed hexamers of SV40 T antigen are active in RNA and origin-DNA unwinding
| Autor: | Hans Stahl, Stephanie Seinsoth, Heike Uhlmann-Schiffler |
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| Rok vydání: | 2002 |
| Předmět: |
Antigens
Polyomavirus Transforming viruses Replication Origin Simian virus 40 Random hexamer Biology Virus Replication Binding Competitive Article Virus Cell Line chemistry.chemical_compound Adenosine Triphosphate Antigen Genetics Animals Binding site RNA Molecular biology RNA Helicase A Microscopy Electron chemistry Viral replication DNA Viral Nucleic Acid Conformation RNA Viral Dimerization RNA Helicases DNA Protein Binding |
| Zdroj: | Nucleic Acids Research. 30:3192-3201 |
| ISSN: | 1362-4962 |
| DOI: | 10.1093/nar/gkf416 |
| Popis: | Preformed hexamers of simian virus 40 (SV40) large tumor antigen (T antigen) constitute the bulk of T antigen in infected cells and are stable under physiological conditions. In spite of this they could not be assigned a function in virus replication or transformation. We report that preformed hexamers represent the active T antigen RNA helicase. Monomers and smaller oligomeric forms of T antigen were inactive due to the lack of hexamer formation under RNA unwinding conditions. In contrast to the immunologically related cellular DEAD-box protein p68, the T antigen RNA helicase is found to act in a much more processive way and it does not catalyze rearrangements of structured RNAs. Thereby, it rather seems to resemble other virus-encoded RNA helicases, like vaccinia virus NPH-II. Surprisingly, in our hands preformed hexamers also strikingly bound to and unwound the SV40 replication origin, pointing to a possible role of preformed hexamers in the initiation step of viral DNA replication. Furthermore, we have detected an extra hexamer-specific, high-affinity T antigen ATP binding site with a very slow exchange rate constant, the function of which is discussed. |
| Databáze: | OpenAIRE |
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