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Schanda, P.

Publications and source records attributed to Schanda, P..

2 recordsLinked to original sources
bioRxiv2018

Dynamics and interactions of ADP/ATP transporter AAC3 in DPC detergent are not functionally relevant

A recent study1 used solution-state NMR spectroscopy to examine the interactions and dynamics of the yeast mitochondrial inner-membrane ADP/ATP carrier, yAAC3. Crystal structures of different AACs, including yAAC3, in a conformation locked with a strong inhibitor (CATR) had been determined before. This putative \"c-state\"2,3 is believed to represent one extreme conformation of an alternating access mechanism, which involves a further and yet elusive second state termed \"m-state\". Characterizing the dynamics between these states is of paramount importance to understand the transport mechanism. The authors refolded yAAC3 from inclusion bodies in the detergent dodecylphosphocholine (DPC), and observed micro-to-millisecond (s-ms) motion in part of yAAC3 using CPMG NMR experiments. The authors propose that this asymmetrically distributed dynamics, involving residues located in thr ...

biophysics↗
bioRxiv2017

Slow conformational exchange and overall rocking motion in ubiquitin protein crystals

Proteins perform their functions in solution but their structures are most frequently studied inside crystals. Here we probe how the crystal packing alters microsecond dynamics, using solid-state NMR measurements and multi-microsecond MD simulations of different crystal forms of ubiquitin. In particular, NEar-Rotary-resonance Relaxation Dispersion (NERRD) experiments probe angular backbone motion, while Bloch-McConnell Relaxation Dispersion data report on fluctuations of the local electronic environment. These experiments and simulations reveal that the packing of the protein can significantly alter the thermodynamics and kinetics of local conformational exchange. Moreover, we report small-amplitude reorientational motion of protein molecules in the crystal lattice with a [~]3-5{degrees} amplitude on a tens-of-microseconds time scale in one of the crystals, but not in others. An intriguing possibility arises that overall motion is to some extent coupled to local dynamics. Our study highlights the importance of considering the packing when analyzing dynamics of crystalline proteins.

biophysics↗