Relationship between hydration induced DNA dynamical transition and DNA-sequence dependent deformability

Nakagawa, Hiroshi   ; Yonetani, Yoshiteru; Nakajima, Kenji  ; Kawamura, Seiko   ; Kikuchi, Tatsuya  ; Inamura, Yasuhiro  ; Kataoka, Mikio; Kono, Hidetoshi

Molecular dynamics simulations and inelastic neutron scattering experiments were conducted on two hydrated DNA dodecamers with distinct deformability; CGCGAATTCGCG and CGCGTTAACGCG. The mean-square displacements of both DNA dodecamers exhibit so-called dynamical transition around 200-240 K and hydration water also exhibits the abrupt increase in the mean-square displacement at the same temperature. The fluctuation amplitude of the central tetramer AATT is smaller, and its relaxation time longer, than that observed on TTAA, suggesting that the AT step is kinetically more stable than the TA step. The sequence dependent DNA base pair step fluctuations appear above the dynamical transition temperature. Therefore, we concluded that the hydration water induces the DNA dynamical transition, and this enhanced motion by hydration is related to the deformability of DNA structure.