Kari Pederson - Furanose Dynamics in the HhaI Methyltransferase Target DNA Studied by Solution and Solid-State NMR Relaxation

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      Publication Details (including relevant citation   information):

      Echodu, D.; Goobes, G.; Shajani, Z.; Pederson, K.; Meints, G.;   Varani, G.; Drobny, G. J. Phys. Chem. B 2008, 112, 13934-13944.


      Both solid-state and solution NMR relaxation measurements are   routinely used to quantify the internal dynamics of biomolecules,   but in very few cases have these two techniques been applied to   the same system, and even fewer attempts have been made so far to   describe the results obtained through these two methods through a   common theoretical framework. We have previously collected both   solution 13C and solid-state 2H relaxation measurements for   multiple nuclei within the furanose rings of several nucleotides   of the DNA sequence recognized by HhaI methyltransferase. The   data demonstrated that the furanose rings within the GCGC   recognition sequence are very flexible, with the furanose rings   of the cytidine, which is the methylation target, experiencing   the most extensive motions. To interpret these experimental   results quantitatively, we have developed a dynamic model of   furanose rings based on the analysis of solid-state 2H line   shapes. The motions are modeled by treating bond reorientations   as Brownian excursions within a restoring potential. By applying   this model, we are able to reproduce the rates of 2H spin-lattice   relaxation in the solid and 13C spin-lattice relaxation in   solution using comparable restoring force constants and internal   diffusion coefficients. As expected, the 13C relaxation rates in   solution are less sensitive to motions that are slower than   overall molecular tumbling than to the details of global   molecular reorientation, but are somewhat more sensitive to   motions in the immediate region of the Larmor frequency. Thus, we   conclude that the local internal motions of this DNA oligomer in   solution and in the hydrated solid state are virtually the same,   and we validate an approach to the conjoint analysis of solution   and solid-state NMR relaxation and line shapes data, with wide   applicability to many biophysical problems.

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