Hsp104 facilitates the endoplasmic-reticulum–associated degradation of disease-associated and aggregation-prone substrates

Lynley M. Doonan, Christopher J. Guerriero, G. Michael Preston, Teresa M. Buck, Netaly Khazanov, Edward A. Fisher, Hanoch Senderowitz, Jeffrey L. Brodsky

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Misfolded proteins in the endoplasmic reticulum (ER) are selected for ER-associated degradation (ERAD). More than 60 disease-associated proteins are substrates for the ERAD pathway due to the presence of missense or nonsense mutations. In yeast, the Hsp104 molecular chaperone disaggregates detergent-insoluble ERAD substrates, but the spectrum of disease-associated ERAD substrates that may be aggregation prone is unknown. To determine if Hsp104 recognizes aggregation-prone ERAD substrates associated with human diseases, we developed yeast expression systems for a hydrophobic lipid-binding protein, apolipoprotein B (ApoB), along with a chimeric protein harboring a nucleotide-binding domain from the cystic fibrosis transmembrane conductance regulator (CFTR) into which disease-causing mutations were introduced. We discovered that Hsp104 facilitates the degradation of ER-associated ApoB as well as a truncated CFTR chimera in which a premature stop codon corresponds to a disease-causing mutation. Chimeras containing a wild-type version of the CFTR domain or a different mutation were stable and thus Hsp104 independent. We also discovered that the detergent solubility of the unstable chimera was lower than the stable chimeras, and Hsp104 helped retrotranslocate the unstable chimera from the ER, consistent with disaggregase activity. To determine why the truncated chimera was unstable, we next performed molecular dynamics simulations and noted significant unraveling of the CFTR nucleotide-binding domain. Because human cells lack Hsp104, these data indicate that an alternate disaggregase or mechanism facilitates the removal of aggregation-prone, disease-causing ERAD substrates in their native environments.

Original languageEnglish
Pages (from-to)1290-1306
Number of pages17
JournalProtein Science
Volume28
Issue number7
DOIs
StatePublished - Jul 2019

Bibliographical note

Publisher Copyright:
© 2019 The Protein Society

Funding

Grant sponsor: Cystic Fibrosis Foundation BRODSKY18G0 SENDER13XX0; Grant sponsor: National Institutes of Health DK061296 DK101584 DK109024 DK79307 GM075061 HL127930.

FundersFunder number
Cystic Fibrosis Foundation BRODSKY18G0 SENDER13XX0BRODSKY18G0 SENDER13XX0
National Institutes of Health DK061296 DK101584 DK109024 DK79307 GM075061 HL127930DK061296 DK101584 DK109024 DK79307 GM075061 HL127930
National Institute of Diabetes and Digestive and Kidney DiseasesR01DK117126

    Keywords

    • AAA-ATPase
    • Hsp104
    • apolipoprotein B
    • cystic fibrosis transmembrane conductance regulator
    • endoplasmic-reticulum–associated degradation
    • molecular chaperone
    • proteasome
    • protein aggregation
    • ubiquitin
    • yeast

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