The effects of supercoiling on the cleavage reaction by eukaryotic DNA topoisomerases I (wheat germ, chicken erythrocyte, and calf thymus) have been analyzed on DNA fragments (0.96 and 2.3 kilobases) encompassing an immunoglobulin kappa light-chain promoter. In one topological condition of the substrate, the absolutely relaxed state, cleavage was found to be impeded. This finding defines the topology-dependent step of the eukaryotic DNA topoisomerase I reaction and shows that for the cleavage reaction topology is more critical than sequence effects. These findings suggest a simple model for the regulation of the DNA topoisomerase I reaction based on topological factors, which may explain the regulatory function of the enzyme in in vivo eukaryotic transcription.
Regulation of the function of eukaryotic DNA topoisomerase I: topological conditions for inactivity / Camilloni, Giorgio; DI MARTINO, E; DI MAURO, Ernesto; Caserta, M.. - In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. - ISSN 0027-8424. - STAMPA. - 86:9(1989), pp. 3080-3084. [10.1073/pnas.86.9.3080]
Regulation of the function of eukaryotic DNA topoisomerase I: topological conditions for inactivity.
CAMILLONI, Giorgio;DI MAURO, Ernesto;
1989
Abstract
The effects of supercoiling on the cleavage reaction by eukaryotic DNA topoisomerases I (wheat germ, chicken erythrocyte, and calf thymus) have been analyzed on DNA fragments (0.96 and 2.3 kilobases) encompassing an immunoglobulin kappa light-chain promoter. In one topological condition of the substrate, the absolutely relaxed state, cleavage was found to be impeded. This finding defines the topology-dependent step of the eukaryotic DNA topoisomerase I reaction and shows that for the cleavage reaction topology is more critical than sequence effects. These findings suggest a simple model for the regulation of the DNA topoisomerase I reaction based on topological factors, which may explain the regulatory function of the enzyme in in vivo eukaryotic transcription.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
