Reconstitution of a mycobacterium tuberculosis proteostasis network highlights essential cofactor interactions with chaperone DnaK Journal Article


Authors: Lupoli, T. J.; Fay, A.; Adura, C.; Glickman, M. S.; Nathan, C. F.
Article Title: Reconstitution of a mycobacterium tuberculosis proteostasis network highlights essential cofactor interactions with chaperone DnaK
Abstract: During host infection, Mycobacterium tuberculosis (Mtb) encounters several types of stress that impair protein integrity, including reactive oxygen and nitrogen species and chemotherapy. The resulting protein aggregates can be resolved or degraded by molecular machinery conserved from bacteria to eukaryotes. Eukaryotic Hsp104/Hsp70 and their bacterial homologs ClpB/DnaK are ATP-powered chaperones that restore toxic protein aggregates to a native folded state. DnaK is essential in Mycobacterium smegmatis, and ClpB is involved in asymmetrically distributing damaged proteins during cell division as a mechanism of survival in Mtb, commending both proteins as potential drug targets. However, their molecular partners in protein reactivation have not been characterized in mycobacteria. Here, we reconstituted the activities of theMtb ClpB/DnaK bichaperone system with the cofactors DnaJ1, DnaJ2, and GrpE and the small heat shock protein Hsp20. We found that DnaJ1 and DnaJ2 activate the ATPase activity of DnaK differently. A point mutation in the highly conserved HPD motif of the DnaJ proteins abrogates their ability to activate DnaK, although the DnaJ2 mutant still binds to DnaK. The purified Mtb ClpB/DnaK system reactivated a heat-denatured model substrate, but the DnaJ HPD mutants inhibited the reaction. Finally, either DnaJ1 or DnaJ2 is required for mycobacterial viability, as is the DnaKactivating activity of a DnaJ protein. These studies lay the groundwork for strategies to target essential chaperone-protein interactions in Mtb, the leading cause of death from a bacterial infection.
Keywords: chaperones; dnak; proteostasis; dnaj proteins; m. tuberculosis
Journal Title: Proceedings of the National Academy of Sciences of the United States of America
Volume: 113
Issue: 49
ISSN: 0027-8424
Publisher: National Academy of Sciences  
Date Published: 2016-12-06
Start Page: E7947
End Page: E7956
Language: English
DOI: 10.1073/pnas.1617644113
PROVIDER: scopus
PMCID: PMC5150378
PUBMED: 27872278
DOI/URL:
Notes: Article -- Export Date: 3 January 2017 -- Source: Scopus
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  1. Allison J Fay
    15 Fay
  2. Michael Glickman
    110 Glickman