The DNAJA2 Substrate Release Mechanism Is Essential for Chaperone-mediated Folding

Baaklini, Imad; Wong, Michael; Hantouche, Christine; Patel, Yogita; Shrier, Alvin; Young, Jason C.

doi:10.1074/jbc.m112.413278

Cited by 47 publications

(58 citation statements)

References 44 publications

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“…The multiple J proteins of eukaryotes are believed to increase the ability of Hsp70 to recognize diverse substrates, albeit with some redundancy (31). Different eukaryotic J proteins produce varying effects on in vitro Hsp70 ATPase and refolding activities (32)(33)(34), or can act as holdases that prevent protein aggregation (35,36). Unique mixtures of J proteins can function as disaggregases (37,38).…”

Section: Significancementioning

confidence: 99%

Reconstitution of a Mycobacterium tuberculosis proteostasis network highlights essential cofactor interactions with chaperone DnaK

Lupoli

Fay

Adura

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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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 the Mtb 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 DnaK-activating 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.

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Section: Significancementioning

confidence: 99%

Reconstitution of a Mycobacterium tuberculosis proteostasis network highlights essential cofactor interactions with chaperone DnaK

Lupoli

Fay

Adura

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…The DNAJ family cochaperones activate ATP hydrolysis and substrate binding by Hsc70/Hsp70, but individual DNAJs are biologically distinct (9). DNAJA2 promotes hERG degradation by non-productively increasing interactions with Hsc70/Hsp70 and its associated E3 ubiquitin ligase CHIP (8,10,11). Hsp70 may also be more active in hERG folding than Hsc70 (12).…”

mentioning

confidence: 99%

Bag1 Co-chaperone Promotes TRC8 E3 Ligase-dependent Degradation of Misfolded Human Ether a Go-Go-related Gene (hERG) Potassium Channels

Hantouche

Williamson

Valinsky

et al. 2017

Journal of Biological Chemistry

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Edited by George N. DeMartinoCardiac long QT syndrome type 2 is caused by mutations in the human ether a go-go-related gene (hERG) potassium channel, many of which cause misfolding and degradation at the endoplasmic reticulum instead of normal trafficking to the cell surface. The Hsc70/Hsp70 chaperones assist the folding of the hERG cytosolic domains. Here, we demonstrate that the Hsp70 nucleotide exchange factor Bag1 promotes hERG degradation by the ubiquitin-proteasome system at the endoplasmic reticulum to regulate hERG levels and channel activity. Dissociation of hERG complexes containing Hsp70 and the E3 ubiquitin ligase CHIP requires the interaction of Bag1 with Hsp70, but this does not involve the Bag1 ubiquitin-like domain. The interaction with Bag1 then shifts hERG degradation to the membrane-anchored E3 ligase TRC8 and its E2-conjugating enzyme Ube2g2, as determined by siRNA screening. TRC8 interacts through the transmembrane region with hERG and decreases hERG functional expression. TRC8 also mediates degradation of the misfolded hERG-G601S disease mutant, but pharmacological stabilization of the mutant structure prevents degradation. Our results identify TRC8 as a previously unknown Hsp70-independent quality control E3 ligase for hERG.

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“…It is believed that Hsp70 and Hsc70 bind with and regulate the hERG channel in a reciprocal way [25] . DNAJA2 and Hop assist in hERG release from Hsc70 [26,27] . Hop also aids the hERG protein in recruiting Hsp90 [27] .…”

Section: Translation and Trafficking Through Er And Golgi Apparatusmentioning

confidence: 99%

Translational toxicology and rescue strategies of the hERG channel dysfunction: biochemical and molecular mechanistic aspects

Zhang

Yang

2014

Acta Pharmacol Sin

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The human ether-à-go-go related gene (hERG) potassium channel is an obligatory anti-target for drug development on account of its essential role in cardiac repolarization and its close association with arrhythmia. Diverse drugs have been removed from the market owing to their inhibitory activity on the hERG channel and their contribution to acquired long QT syndrome (LQTS). Moreover, mutations that cause hERG channel dysfunction may induce congenital LQTS. Recently, an increasing number of biochemical and molecular mechanisms underlying hERG-associated LQTS have been reported. In fact, numerous potential biochemical and molecular rescue strategies are hidden within the biogenesis and regulating network. So far, rescue strategies of hERG channel dysfunction and LQTS mainly include activators, blockers, and molecules that interfere with specific links and other mechanisms. The aim of this review is to discuss the rescue strategies based on hERG channel toxicology from the biochemical and molecular perspectives.

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The DNAJA2 Substrate Release Mechanism Is Essential for Chaperone-mediated Folding

Cited by 47 publications

References 44 publications

Reconstitution of a Mycobacterium tuberculosis proteostasis network highlights essential cofactor interactions with chaperone DnaK

Reconstitution of a Mycobacterium tuberculosis proteostasis network highlights essential cofactor interactions with chaperone DnaK

Bag1 Co-chaperone Promotes TRC8 E3 Ligase-dependent Degradation of Misfolded Human Ether a Go-Go-related Gene (hERG) Potassium Channels

Translational toxicology and rescue strategies of the hERG channel dysfunction: biochemical and molecular mechanistic aspects

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