"Invisible" Conformers of an Antifungal Disulfide Protein Revealed by Constrained Cold and Heat Unfolding, CEST-NMR Experiments, and Molecular Dynamics Calculations

Ádám Fizil, Zoltán Gáspári, Terézia Barna, Florentine Marx, Gyula Batta

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Transition between conformational states in proteins is being recognized as a possible key factor of function. In support of this, hidden dynamic NMR structures were detected in several cases up to populations of a few percent. Here, we show by two- and three-state analysis of thermal unfolding, that the population of hidden states may weight 20-40 % at 298 K in a disulfide-rich protein. In addition, sensitive 15N-CEST NMR experiments identified a low populated (0.15 %) state that was in slow exchange with the folded PAF protein. Remarkably, other techniques failed to identify the rest of the NMR "dark matter". Comparison of the temperature dependence of chemical shifts from experiments and molecular dynamics calculations suggests that hidden conformers of PAF differ in the loop and terminal regions and are most similar in the evolutionary conserved core. Our observations point to the existence of a complex conformational landscape with multiple conformational states in dynamic equilibrium, with diverse exchange rates presumably responsible for the completely hidden nature of a considerable fraction.

Original languageEnglish
Pages (from-to)5136-5144
Number of pages9
JournalChemistry - A European Journal
Volume21
Issue number13
DOIs
Publication statusPublished - Mar 23 2015

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Keywords

  • NMR spectroscopy
  • conformation analysis
  • molecular modeling
  • protein folding
  • protein structures

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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