TY - JOUR
T1 - DNA strand cleavage is required for replication fork arrest by a frozen topoisomerase-quinolone-DNA ternary complex
AU - Hiasa, Hiroshi
AU - Yousef, Diana O.
AU - Marians, Kenneth J.
PY - 1996
Y1 - 1996
N2 - The formation of a topoisomerase-quinolone-DNA ternary complex leads to cell death. We show here that an active strand breakage and reunion activity is required for formation of a norfloxacin-topoisomerase IV-DNA ternary complex that can arrest the progression of replication forks in vitro. Mutant topoisomerases containing either an active site mutation, a quinolone resistance-conferring mutation, or both, could all bind DNA as well as the wild-type, but unlike the wild-type, could not halt replication fork progression. The collision between the replication fork and the frozen topoisomerase converted the cleavable complex to a nonreversible form but did not generate a double-stranded break. Thus, the cytotoxicity of this class of topoisomerase inhibitors likely results from a two-step process: (i) conversion of the frozen topoisomerase-quinolone-DNA ternary complex to an unreversible form; and (ii) generation of a double-strand break by subsequent denaturation of the topoisomerase, perhaps by an aborted repair attempt.
AB - The formation of a topoisomerase-quinolone-DNA ternary complex leads to cell death. We show here that an active strand breakage and reunion activity is required for formation of a norfloxacin-topoisomerase IV-DNA ternary complex that can arrest the progression of replication forks in vitro. Mutant topoisomerases containing either an active site mutation, a quinolone resistance-conferring mutation, or both, could all bind DNA as well as the wild-type, but unlike the wild-type, could not halt replication fork progression. The collision between the replication fork and the frozen topoisomerase converted the cleavable complex to a nonreversible form but did not generate a double-stranded break. Thus, the cytotoxicity of this class of topoisomerase inhibitors likely results from a two-step process: (i) conversion of the frozen topoisomerase-quinolone-DNA ternary complex to an unreversible form; and (ii) generation of a double-strand break by subsequent denaturation of the topoisomerase, perhaps by an aborted repair attempt.
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U2 - 10.1074/jbc.271.42.26424
DO - 10.1074/jbc.271.42.26424
M3 - Article
C2 - 8824300
AN - SCOPUS:0029859964
SN - 0021-9258
VL - 271
SP - 26424
EP - 26429
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 42
ER -