title: Opposing Effects of Multivalent Ions on the Flexibility of DNA and RNA.
abstract: Increasing the concentration of counterions (salt) is known to reduce the bending persistence length of DNA. Here we use atomistic molecular dynamics simulations to predict that multivalent counterions have the opposite effect on double-stranded RNA, increasing its bending rigidity by at least 30%. This counterintuitive effect is observed for various tri- and tetravalent ions alike, and is robust to methodological details and the RNA sequence. In contrast to DNA, multivalent counterions bind inside the RNA major groove, causing significant contraction of the molecule along its helical axis-as a result, its further deformation due to bending becomes energetically more expensive compared to bending without bound multivalent ions. Thus, the relationship between mechanical properties of a charged polymer and its ionic atmosphere may be richer than previously thought.
authors.affiliation: Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Aleksander V
authors.initials: AV
authors.lastname: Drozdetski
authors.affiliation: Department of Computer Science, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Igor S
authors.initials: IS
authors.lastname: Tolokh
authors.affiliation: School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853-3501, USA.
authors.forename: Lois
authors.initials: L
authors.lastname: Pollack
authors.affiliation: Advanced Computing, Mathematics, and Data Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.|Division of Applied Mathematics, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Nathan
authors.initials: N
authors.lastname: Baker
authors.affiliation: Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, USA.|Department of Computer Science, Virginia Tech, Blacksburg, Virginia 24061, USA.|Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Onufriev
mesh_terms: D001483:Base Sequence; D055592:Biophysical Phenomena; D004247:DNA / Q000737:chemistry*; D007477:Ions; D011108:Polymers; D012330:RNA, Double-Stranded / Q000737:chemistry*
chemical_list: D007477:Ions; D011108:Polymers; D012330:RNA, Double-Stranded; D004247:DNA