TY - JOUR
T1 - Interactions between DNA helicases and frozen topoisomerase IV- quinolone-DNA ternary complexes
AU - Shea, Molly E.
AU - Hiasa, Hiroshi
PY - 1999/8/6
Y1 - 1999/8/6
N2 - Collisions between replication forks and topoisomerase-drug-DNA ternary complexes result in the inhibition of DNA replication and the conversion of the normally reversible ternary complex to a nonreversible form. Ultimately, this can lead to the double strand break formation and subsequent cell death. To understand the molecular mechanisms of replication fork arrest by the ternary complexes, we have investigated molecular events during collisions between DNA helicases and topoisomerase-DNA complexes. A strand displacement assay was employed to assess the effect of topoisomerase IV (Topo IV)- norfloxacin-DNA ternary complexes on the DnaB, T7 gene 4 protein, SV40 T- antigen, and UvrD DNA helicases. The ternary complexes inhibited the strand displacement activities of these DNA helicases. Unlike replication fork arrest, however, this general inhibition of DNA helicases by Topo IV- norfloxacin-DNA ternary complexes did not require the cleavage and reunion activity of Topo IV. We also examined the reversibility of the ternary complexes after collisions with these DNA helicases. UvrD converted the ternary complex to a nonreversible form, whereas DnaB, T7 gene 4 protein, and SV40 T-antigen did not. These results suggest that the inhibition of DnaB translocation may be sufficient to arrest the replication fork progression but it is not sufficient to generate cytotoxic DNA lesion.
AB - Collisions between replication forks and topoisomerase-drug-DNA ternary complexes result in the inhibition of DNA replication and the conversion of the normally reversible ternary complex to a nonreversible form. Ultimately, this can lead to the double strand break formation and subsequent cell death. To understand the molecular mechanisms of replication fork arrest by the ternary complexes, we have investigated molecular events during collisions between DNA helicases and topoisomerase-DNA complexes. A strand displacement assay was employed to assess the effect of topoisomerase IV (Topo IV)- norfloxacin-DNA ternary complexes on the DnaB, T7 gene 4 protein, SV40 T- antigen, and UvrD DNA helicases. The ternary complexes inhibited the strand displacement activities of these DNA helicases. Unlike replication fork arrest, however, this general inhibition of DNA helicases by Topo IV- norfloxacin-DNA ternary complexes did not require the cleavage and reunion activity of Topo IV. We also examined the reversibility of the ternary complexes after collisions with these DNA helicases. UvrD converted the ternary complex to a nonreversible form, whereas DnaB, T7 gene 4 protein, and SV40 T-antigen did not. These results suggest that the inhibition of DnaB translocation may be sufficient to arrest the replication fork progression but it is not sufficient to generate cytotoxic DNA lesion.
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U2 - 10.1074/jbc.274.32.22747
DO - 10.1074/jbc.274.32.22747
M3 - Article
C2 - 10428858
AN - SCOPUS:0033529492
VL - 274
SP - 22747
EP - 22754
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 32
ER -