Session FOB. There are 5 abstracts in this session.

Session: Biomolecular Dynamics 2, time: 10:45-11:10
Conformational Excited States in DNA Dictate Spontaneous Mutation Rates during Replication
Hashim Al-Hashimi
Duke Univ School of Medicine, Durham, NC

Tautomer and anionic Watson-Crick like mismatches mimic the geometry of canonical Watson Crick base pairs and can therefore potentially evade fidelity checkpoints during replication, transcription, and translation. Although these unusual base pairs were implicated as triggers of spontaneous mutations by Watson and Crick even before DNA polymerase was discovered, their very existence and roles in replication has remained elusive. Here, by using R1rho NMR relaxation dispersion experiments, we have uncovered a network of tautomeric and anionic Watson-Crick dG-dT mismatches, and determined their relative contributions to substitution mutations during nucleotide selection.

Session: Biomolecular Dynamics 2, time: 11:10-11:35
Cavities, context and protein conformational landscapes. 
Kelly Jenkins1; Sean Klein2; Siwen Zhang1; Martin Fossat1; Doug Barrick2; Catherine Royer1
1Rensselaer Polytechnic Institute, Troy, NY; 2Johns Hopkins University, Baltimore, MD
Introduction of cavities into the protein cores destabilizes the folded state relative to the unfolded state by about 1.1 kcal/mole CH2 group removed. Such substitutions have been used widely in combination with kinetics measurements to obtain structural information concerning folding transition state ensembles. Most studies have relied on chemical denaturation and CD or fluorescence. Here we probe the effects of cavity creating substitutions on the folding cooperativity of a leucine rich repeat protein, pp32, using a combination of pressure perturbation and site-specific NMR. While the degree of global destabilization is similar for substitutions across the protein's structure, we ind that their effect on folding cooperativity is highly context dependent.

Session: Biomolecular Dynamics 2, time: 11:35-12:00
Real-time multidimensional NMR: a complementary off-equilibrium tool for structural biology 
Rémi Franco1; Enrico Rennella2; Adrien Favier1; Paul Schanda1; Bernhard Brutscher1
1IBS / NMR, Grenoble, France; 2University of Toronto, Toronto, Canada
Real-time multidimensional NMR provides a powerful tool for investigating, at atomic resolution, conformational transitions that involve energy barriers of more than a few kcal/mol. The conformational transition is induced by a rapid change in the sample conditions, followed by continuous NMR data acquisition to monitor changes in NMR observables over time. Real-time NMR has benefited substantially from fast multidimensional NMR data acquisition methods, e.g. the SOFAST and BEST techniques developed in our laboratory.
I will present some recent advancement we have made in this field and demonstrate how these tools proved useful for characterizing the major folding intermediate of the amyloidogenic protein β2 microglobulin, and for investigating at single-nucleotide resolution the RNA-melting activity of the bacterial cold shock protein CspA.

Session: Biomolecular Dynamics 2, time: 12:00-12:15
NMR Studies of Hierarchical Protein Dynamics
Jayasubba Reddy Yarava1; Baptiste Busi1; Albert Hofstetter1; Francois Freymond1; Michel-Andreas Geiger2; Hartmut Oschkinat2; Martin Blackledge3; Lyndon Emsley1
1EPFL, Switzerland, Lausanne, Switzerland; 2Leibniz-Institut für Molekulare Pharmakologie (FMP, Berlin-Buch Robert-Roessle-Str.10, Berlin, Germany; 3Université Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
Understanding dynamics in proteins is crucial to describe their function, since their activity depends on both structural and dynamical properties. Lewandowski et al. introduced an approach using temperature dependent magic angle spinning multinuclear solid-state NMR relaxation measurements with sixteen different probes, and successfully characterized the hierarchy of dynamic processes in the protein GB1. Here, we investigate the robustness and reproducibility of the method and we expand the approach to include measurements at several different magnetic field strengths. Furthermore, we take a step towards evaluating the universality of the hierarchy in dynamics of proteins by extending the method to a second microcrystalline protein (SH3), to a disordered protein and to a membrane protein.

Session: Biomolecular Dynamics 2, time: 12:15-12:30
Structural dynamics of potassium ion channels revealed by side-chain methyl 13C-1H multiple quantum relaxation analyses 
Yuki Toyama; Hanaho Kano; Yoko Mase; Mariko Yokogawa; Masanori Osawa; Ichio Shimada
Dept. of Pharm., Univ. of Tokyo, Bunkyo-Ku, Japan
K+ channels are not static and exchanging between functionally different states, and interconversion between these states play critical roles in their biological functions. However, since ion channel proteins usually have large molecular weights, conventional NMR techniques are usually difficult to apply. To characterize the chemical exchange processes of K+ channels, we established a new methyl-based NMR method, utilizing differential 13C-1H multiple-quantum (MQ) relaxation rates and a heteronuclear double resonance pulse technique. We applied the method to an inwardly-rectifying potassium channel, which has an apparent molecular weight of over 200 K as a functional tetrameric form, and successfully identified the regions that exist in a chemical exchange process on millisecond time scale. (Toyama et al, JACS 138(7), 2302-2311)