Inter-DNA attraction mediated by divalent counterions.
Can nonspecifically bound divalent counterions induce attraction between DNA strands? Here, we present experimental evidence demonstrating attraction between short DNA strands mediated by Mg2+ ions. Solution small angle x-ray scattering data collected as a function of DNA concentration enable model independent extraction of the second virial coefficient. As the [Mg2+] increases, this coefficient turns from positive to negative reflecting the transition from repulsive to attractive inter-DNA interaction. This surprising observation is corroborated by independent light scattering experiments. The dependence of the observed attraction on experimental parameters including DNA length provides valuable clues to its origin.
School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA.
Xiangyun
X
Qiu
Kurt
K
Andresen
Lisa W
LW
Kwok
Jessica S
JS
Lamb
Hye Yoon
HY
Park
Lois
L
Pollack
D004247:DNA / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D014961:X-Ray Diffraction
D004247:DNA; D008274:Magnesium