Requirement of DNA topoisomerases for in vitro chromatin assembly by 3T6 mouse cell extracts
Nuclear extracts of 3T6 mouse cells were able to assemble in vitro minichromosomes which displayed a 150‐bp periodicity. Activities of both DNA topoisomerases I and II were detected in these extracts. When a supercoiled pUC DNA was added, it was first relaxed in less than 3 min, then slowly supercoi...
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| Autores principales: | , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00142956_v181_n2_p531_CACERES |
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| Sumario: | Nuclear extracts of 3T6 mouse cells were able to assemble in vitro minichromosomes which displayed a 150‐bp periodicity. Activities of both DNA topoisomerases I and II were detected in these extracts. When a supercoiled pUC DNA was added, it was first relaxed in less than 3 min, then slowly supercoiled again in 1–4 h. Both reactions occurred either in the absence or the presence of added Mg2+ and/or ATP, they were not blocked by DNA topoisomerase II inhibitors and they were inhibited by an antiserum against DNA topoisomerase I and by camptothecin. These findings led us to propose that, under our in vitro assay conditions, chromatin assembly is mainly carried out by a DNA topoisomerase I. Copyright © 1989, Wiley Blackwell. All rights reserved |
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