An S/T motif controls reversible oligomerization of the Hsp40 chaperone DNAJB6b through subtle reorganization of a β sheet backbone

Proc Natl Acad Sci U S A. 2020 Dec 1;117(48):30441-30450. doi: 10.1073/pnas.2020306117. Epub 2020 Nov 16.


Chaperone oligomerization is often a key aspect of their function. Irrespective of whether chaperone oligomers act as reservoirs for active monomers or exhibit a chaperoning function themselves, understanding the mechanism of oligomerization will further our understanding of how chaperones maintain the proteome. Here, we focus on the class-II Hsp40, human DNAJB6b, a highly efficient inhibitor of protein self-assembly in vivo and in vitro that forms functional oligomers. Using single-quantum methyl-based relaxation dispersion NMR methods we identify critical residues for DNAJB6b oligomerization in its C-terminal domain (CTD). Detailed solution NMR studies on the structure of the CTD showed that a serine/threonine-rich stretch causes a backbone twist in the N-terminal β strand, stabilizing the monomeric form. Quantitative analysis of an array of NMR relaxation-based experiments (including Carr-Purcell-Meiboom-Gill relaxation dispersion, off-resonance R profiles, lifetime line broadening, and exchange-induced shifts) on the CTD of both wild type and a point mutant (T142A) within the S/T region of the first β strand delineates the kinetics of the interconversion between the major twisted-monomeric conformation and a more regular β strand configuration in an excited-state dimer, as well as exchange of both monomer and dimer species with high-molecular-weight oligomers. These data provide insights into the molecular origins of DNAJB6b oligomerization. Further, the results reported here have implications for the design of β sheet proteins with tunable self-assembling properties and pave the way to an atomic-level understanding of amyloid inhibition.

Keywords: Hsp40 chaperones; conformational transitions; oligomerization; relaxation-based NMR; short-lived excited states.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Amino Acid Motifs*
  • Amino Acid Sequence
  • HSP40 Heat-Shock Proteins / chemistry*
  • HSP40 Heat-Shock Proteins / metabolism
  • Kinetics
  • Models, Molecular*
  • Protein Binding
  • Protein Conformation
  • Protein Conformation, beta-Strand*
  • Protein Interaction Domains and Motifs*
  • Protein Multimerization*


  • HSP40 Heat-Shock Proteins

Associated data

  • figshare/10.6084/m9.figshare.13012682