Adenovirus Infection Elevates Levels of Cellular Topoisomerase I
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We have developed a specific, sensitive, and quantitative assay for topoisomerase I, which is based on the formation of a covalent enzyme-DNA intermediate. Our assay measures the quantitative transfer of 32P radioactivity from 32P-labeled DNA to topoisomerase I. Since 32P-labeled topoisomerase molecules are resolved by NaDodSO4/PAGE, HeLa topoisomerase I (100 kDa) and calf thymus topoisomerase I (82 kDa) can be quantitatively assayed in the same reaction mixture. The assay can detect at least 0.3 ng (3 fmol) of topoisomerase I. We have used our assay to measure the levels of topoisomerase I activity in crude extracts of nuclei prepared from uninfected, adenovirus-infected, and adenovirus-transformed human cells. The evidence suggests that an adenovirus early gene product, presumably a protein encoded in early region 1A (E1A), increases cellular topoisomerase I activity at least 10-fold. Immunoblotting analysis with antiserum against calf thymus topoisomerase I shows that the increase in activity is due to an increase in the amount of enzyme.
The predominant form of mammalian DNA topoisomerase I in vivo has a molecular mass of 100 kDa.
Samuels D, Shimizu N Mol Biol Rep. 1994; 19(2):99-103.
PMID: 8072496 DOI: 10.1007/BF00997154.
Adenovirus 2 peptide IX gene is expressed only on replicated DNA molecules.
Matsui T, Murayama M, Mita T Mol Cell Biol. 1986; 6(12):4149-54.
PMID: 3025639 PMC: 367193. DOI: 10.1128/mcb.6.12.4149-4154.1986.
White E, Stillman B J Virol. 1987; 61(2):426-35.
PMID: 2949088 PMC: 253966. DOI: 10.1128/JVI.61.2.426-435.1987.
Factors affecting amplification of BK virus episomal vectors in human cells. Brief report.
Grossi M, Caputo A, Paolini L, Balboni P, Gerna G, Pagnani M Arch Virol. 1988; 99(3-4):249-59.
PMID: 2835949 DOI: 10.1007/BF01311074.
Interactions of minute virus of mice and adenovirus with host nucleoli.
Walton T, Moen Jr P, Fox E, Bodnar J J Virol. 1989; 63(9):3651-60.
PMID: 2760977 PMC: 250955. DOI: 10.1128/JVI.63.9.3651-3660.1989.