Unveiling the activation dynamics of a fold-switch bacterial glycosyltransferase by 19F NMR

J Biol Chem. 2020 Jul 17;295(29):9868-9878. doi: 10.1074/jbc.RA120.014162. Epub 2020 May 20.


Fold-switch pathways remodel the secondary structure topology of proteins in response to the cellular environment. It is a major challenge to understand the dynamics of these folding processes. Here, we conducted an in-depth analysis of the α-helix-to-β-strand and β-strand-to-α-helix transitions and domain motions displayed by the essential mannosyltransferase PimA from mycobacteria. Using 19F NMR, we identified four functionally relevant states of PimA that coexist in dynamic equilibria on millisecond-to-second timescales in solution. We discovered that fold-switching is a slow process, on the order of seconds, whereas domain motions occur simultaneously but are substantially faster, on the order of milliseconds. Strikingly, the addition of substrate accelerated the fold-switching dynamics of PimA. We propose a model in which the fold-switching dynamics constitute a mechanism for PimA activation.

Keywords: 19F NMR; carbohydrate active enzymes; conformational dynamics; enzyme catalysis; glycosyltransferases; protein fold-switching, protein dynamics; protein function; protein structure; relaxation dispersion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry*
  • Mannosyltransferases / chemistry*
  • Molecular Dynamics Simulation*
  • Mycobacterium smegmatis / enzymology*
  • Nuclear Magnetic Resonance, Biomolecular
  • Protein Folding*


  • Bacterial Proteins
  • Mannosyltransferases
  • phosphatidyl-myo-inositol mannosyltransferase PimA, Mycobacterium smegmatis

Associated data

  • PDB/4NC9
  • PDB/2GEJ