Skip Navigation

This Article
Right arrow Full Text Freely available
Right arrow Print PDF (326K) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (8)
Right arrowRequest Permissions
Right arrow Commercial Re-use Guidelines
for Open Access NAR Content
Google Scholar
Right arrow Articles by Christensen, M. O.
Right arrow Articles by Mielke, C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Christensen, M. O.
Right arrow Articles by Mielke, C.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Nucleic Acids Research, 2003, Vol. 31, No. 24 7255-7263
© 2003 Oxford University Press

Article

Residues 190–210 of human topoisomerase I are required for enzyme activity in vivo but not in vitro

Morten O. Christensen, Hans U. Barthelmes, Fritz Boege and Christian Mielke*

Institute of Clinical Chemistry and Laboratory Diagnostics, Heinrich–Heine–University, Medical School, Moorenstraße 5, D-40225 Duesseldorf, Germany

*To whom correspondence should be addressed. Tel: +49 211 81 19323; Fax: +49 211 81 18021; Email: christian.mielke{at}med.uni-duesseldorf.de

DNA-topoisomerase I (topo I) unwinds the DNA- double helix by cutting one strand and allowing rotation of the other. In vitro, this function does not require the N-terminal domain of the enzyme, which is believed to regulate cellular properties. To assess this role, we studied the cellular distribution and mobility of green fluorescent protein-chimera of human topo I lacking either the entire N-terminal domain or a portion of it. We find that topo I truncated up to position 210 is not stabilized by camptothecin in covalent DNA-complexes inside a living cell, whereas in vitro it retains full DNA-relaxation activity, and is targeted by camptothecin in the usual manner. This difference is not shared with a fragment lacking the N-terminal domain up to position 190, indicating that residues 190–210 play a crucial role for the activity of the enzyme in its physiological environment, but not in vitro. Since it is impossible to discriminate in vivo whether this region is required for topo I to form covalent DNA intermediates in the cell, or just for camptothecin to bind and stabilize such complexes, we could not explain precisely these cellular observations. However, inactivity in vivo of the enzyme lacking this region is indicated by a lesser cytotoxicity.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Nucleic Acids ResHome page
R. M. Linka, A. C.G. Porter, A. Volkov, C. Mielke, F. Boege, and M. O. Christensen
C-Terminal regions of topoisomerase II{alpha} and II{beta} determine isoform-specific functioning of the enzymes in vivo
Nucleic Acids Res., June 28, 2007; 35(11): 3810 - 3822.
[Abstract] [Full Text] [PDF]

Home page
 Nucleic Acids ResHome page
L. Sari and I. Andricioaei
Rotation of DNA around intact strand in human topoisomerase I implies distinct mechanisms for positive and negative supercoil relaxation
Nucleic Acids Res., November 27, 2005; 33(20): 6621 - 6634.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
H. U. Barthelmes, M. Habermeyer, M. O. Christensen, C. Mielke, H. Interthal, J. J. Pouliot, F. Boege, and D. Marko
TDP1 Overexpression in Human Cells Counteracts DNA Damage Mediated by Topoisomerases I and II
J. Biol. Chem., December 31, 2004; 279(53): 55618 - 55625.
[Abstract] [Full Text] [PDF]

Home page
 Biophys. JHome page
G. Chillemi, M. Redinbo, A. Bruselles, and A. Desideri
Role of the Linker Domain and the 203-214 N-Terminal Residues in the Human Topoisomerase I DNA Complex Dynamics
Biophys. J., December 1, 2004; 87(6): 4087 - 4097.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
M. O. Christensen, R. M. Krokowski, H. U. Barthelmes, R. Hock, F. Boege, and C. Mielke
Distinct Effects of Topoisomerase I and RNA Polymerase I Inhibitors Suggest a Dual Mechanism of Nucleolar/Nucleoplasmic Partitioning of Topoisomerase I
J. Biol. Chem., May 21, 2004; 279(21): 21873 - 21882.
[Abstract] [Full Text] [PDF]


Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.