High-Pressure NMR Reveals Volume and Compressibility Differences Between Two Stably Folded Protein Conformations

Xingjian Xu, Donald Gagné, James M. Aramini, Kevin H. Gardner

Research output: Contribution to journalArticlepeer-review

Abstract

Proteins often interconvert between different conformations in ways critical to their function. However, manipulating the equilibrium positions and kinetics of such conformational transitions has been traditionally challenging. Pressure is an effective thermodynamic variable for favoring the population of high energy protein conformational states with smaller volumes, as elegantly demonstrated in its use for biophysical studies of unfolding transitions. Here, we investigate the pressure-dependent effects of the interconversion of two stably-folded conformations of the Y456T variant of the aryl hydrocarbon receptor nuclear translocator (ARNT) Period/ARNT/Single-minded PAS-B domain. We previously discovered that ARNT PAS-B Y456T spontaneously interconverts between two structures primarily differing by a three-residue b-strand slip, inverting its topology in the process. This change collapses the internal cavities of the WT-like (WT) conformation of this protein as it adopts the slipped conformation (SLIP). Using pressure-NMR to conduct thermodynamic and kinetic analyses of the interconversion of ARNT PAS-B, we provide data that support two key predictions of this process: the SLIP conformation is both smaller and less compressible than the WT conformation, and the interconversion proceeds through a chiefly-unfolded intermediate state. We also find that the pressure-dependent NMR chemical shift changes and the residue-specific compressibility both predict which amino acid residues are near protein cavities. We demonstrate that pressure-NMR is a powerful approach for characterizing protein conformational switching and can provide unique information that is not easily accessible through other techniques.

Original languageEnglish (US)
JournalUnknown Journal
DOIs
StatePublished - Jul 30 2020

Keywords

  • ARNT
  • Cavities
  • Compressibilities
  • Conformational change
  • High pressure NMR
  • Per-ARNT-Sim domains

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • Immunology and Microbiology(all)
  • Neuroscience(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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