Tryptophane-205 of human topoisomerase I is essential for camptothecin inhibition of negative but not positive supercoil removal.

Tryptophane-205 of human topoisomerase I is essential for camptothecin inhibition of negative but not positive supercoil removal. Research Abstract Details 

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Tryptophane-205 of human topoisomerase I is essential for camptothecin inhibition of negative but not positive supercoil removal. Abstract Text:

Rikke From ,Christopher Veigaard, Andersen,A Kathleen McClendon,Amanda C Gentry,Anni Hangaard Andersen,Neil Osheroff,Tinna Stevnsner,Birgitta Ruth Knudsen,

Positive supercoils are introduced in cellular DNA in front of and negative supercoils behind tracking polymerases. Since DNA purified from cells is normally under-wound, most studies addressing the relaxation activity of topoisomerase I have utilized negatively supercoiled plasmids. The present report compares the relaxation activity of human topoisomerase I variants on plasmids containing equal numbers of superhelical twists with opposite handedness. We demonstrate that the wild-type enzyme and mutants lacking amino acids 1-206 or 191-206, or having tryptophane-205 replaced with a glycine relax positive supercoils faster than negative supercoils under both processive and distributive conditions. In contrast to wild-type topoisomerase I, which exhibited camptothecin sensitivity during relaxation of both negative and positive supercoils, the investigated N-terminally mutated variants were sensitive to camptothecin only during removal of positive supercoils. These data suggest different mechanisms of action during removal of supercoils of opposite handedness and are consistent with a recently published simulation study [Sari and Andricioaei (2005) Nucleic Acids Res., 33, 6621-6634] suggesting flexibility in distinct parts of the enzyme during clockwise or counterclockwise strand rotation.

Tryptophane-205 of human topoisomerase I is essential for camptothecin inhibition of negative but not positive supercoil removal. Publishing Authors By Initials

RF ,C Veigaard,FF Andersen,AK McClendon,AC Gentry,AH Andersen,N Osheroff,T Stevnsner,BR Knudsen,

For similar amino acids, peptides, and proteins: amino acids: amino acids, cyclic: amino acids, aromatic: tryptophan research abstracts see: amino acids, peptides, and proteins: amino acids: amino acids, cyclic: amino acids, aromatic: tryptophan research

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Tryptophane-205 of human topoisomerase I is essential for camptothecin inhibition of negative but not positive supercoil removal. Journal Published:

PUBLICATION TYPE: Research Support, Non-U.S. Gov

Journal: Nucleic acids research

VOLUME: 35

Page Numbers: 6170-80

Journal Abbreviation: Nucleic Acids Res.

ISSN: 1362-4962

DAY: 7

MONTH: 09

YEAR: 2007

Tryptophane-205 of human topoisomerase I is essential for camptothecin inhibition of negative but not positive supercoil removal. Information

Number of References:

LANGUAGE: eng

NlmUniqueID: 411011

Tryptophane-205 of human topoisomerase I is essential for camptothecin inhibition of negative but not positive supercoil removal. Keywords Mesh Terms:

KEYWORDS: Tryptophan

MESH TERMS: chemistry

Chemical & Substance for Abstract: Tryptophane-205 of human topoisomerase I is essential for camptothecin inhibition of negative but not positive supercoil removal. Information

Substance Name: DNA Topoisomerases, Type I, Eukaryotic

Registry Number: EC 5.99.1.-

Grant and Affiliation Information for Tryptophane-205 of human topoisomerase I is essential for camptothecin inhibition of negative but not positive supercoil removal.

AFFILIATION: Department of Molecular Biology, Aarhus University, C. F. Møllers Allé Bldg. 130, 8000 Arhus C, Denmark.

Country: England

AGENCY: United States NIGMS

GRANT: GM33944

ACRONYM: GM

MEDLINETA: Nucleic Acids Res

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