Visualization of complexes of Hoechst 33258 and DNA duplexes in solution by atomic force microscopy.
Tertiary structure changes in DNA duplexes, induced by Hoechst 33258 binding, have been examined by the use of atomic force microscopy. Besides minor groove binding, which is an established mode of binding for this drug, Hoechst 33258 has now been found to show another binding mode, which causes an unwinding of the duplex. When the drug concentration is as high as 0.5 microg/ml, the Hoechst 33258 molecule seems to function as a clamp for two DNA chains and forms a condensate. The condensate was found to have a toroidal shape. By surveying more than 100 microscopic images of such condensates formed in I microg/ml drug solution, a mechanism of toroidal condensate formation has been proposed.
Utsuno
Kuniharu
K
High-Tech Research Center, College of Science and Engineering, Iwaki Meisei University, Fukushima, Japan.
Tsuboi
Masamichi
M
Katsumata
Shunji
S
Iwamoto
Toschitake
T
D006690:Bisbenzimidazole / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D012996:Solutions
D005456:Fluorescent Dyes; D012996:Solutions; D004247:DNA; D006690:Bisbenzimidazole