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Single-Cell Biophysics: Measurement, Modulation, and Modeling
Poster Abstracts
60
31-POS
Board 16
Dynamic Analysis of DNA and Topoisomerase II Interaction Based on Fluorescence
Fluctuation and Single Molecule Detection
Wan-Chen Huang
1
, Chun-Ying Lee
2
, Tao-Shih Hsieh
1,2
.
1
Academia Sinica, Taipei, Taiwan,
2
National Taiwan University, Taipei, Taiwan.
Topoisomerase 2 (Top2) is known as anticancer drug target due to its highly demanded on
resolving DNA tangling problems during cell division. These enzymes regulate DNA topology
by transiently breaking one DNA double strand (cleavage), allowing the second double strand to
pass through the opened DNA gate (opening), and then closing the gate by rejoining the broken
end. Previous studies defined the Top2 function mainly at DNA cleavage and re-ligation steps,
however, whether the cofactors and Top2 drugs interfere the DNA dynamics at the opening and
closing steps remain unclear. Here, we used fluorescence correlation spectroscopy (FCS) and
Förster resonance energy transfer (FRET) in combination to examine the cofactor effects on the
interaction of Top2 and DNA, and in addition used the single molecule FRET (smFRET) method
to observe the opening and closing of DNA gate. Our results demonstrated that both types of
anticancer drugs, teniposide (VM26) and dexrazoxane (ICRF187) can interfere the rate of DNA
gate dynamics by shortening the dwell time at closing state. Moreover, binding of AMPPNP
induced DNA gate dynamics, which is previously unaddressed. These findings unmask the Top2
dynamics after N-gate closure and reveal the potential mechanism of action of Top2 drugs.