Cookies on this website
We use cookies to ensure that we give you the best experience on our website. If you click 'Continue' we'll assume that you are happy to receive all cookies and you won't see this message again. Click 'Find out more' for information on how to change your cookie settings.

Several recent studies have shown that human topoisomerase I (htopoI) can recognize various DNA lesions and thereby form a covalent topoisomerase I-DNA complex, which is known to be detrimental to cells. We have investigated whether htopoI recognizes another htopoI that is covalently trapped on a DNA substrate. For this purpose we created an artificial DNA substrate containing a specific topoisomerase I binding sequence, where the enzyme was trapped in the covalently bound form. We demonstrate that, in vitro, free htopoI stimulates the formation of an additional cleavage complex immediately upstream of the covalently bound topoisomerase I. The predominant distance between the two cleavage sites is 13 nt. In addition we find that these two enzymes may form direct protein-protein contacts and we propose that these may be mediated through the formation of a dimer by domain swapping involving the C-terminal and the core domains. Finally, we discuss the possibility that the double cleavage reaction may be the initial step for the removal of the recognized cleavage complex.

Type

Journal article

Journal

Nucleic Acids Res

Publication Date

01/08/2001

Volume

29

Pages

3195 - 3203

Keywords

Animals, Baculoviridae, Base Sequence, Binding Sites, Camptothecin, Catalysis, Cell Line, DNA, DNA Topoisomerases, Type I, DNA-Binding Proteins, Dimerization, Endopeptidase K, Humans, Molecular Sequence Data, Nucleic Acid Conformation, Recombinant Proteins, Saccharomyces cerevisiae, Substrate Specificity, Subtilisin, Titrimetry, Topoisomerase I Inhibitors, Trypsin