Structural and biological interaction of HSC-70 protein with phosphatidylserine in endosomal microautophagy

Kateryna Morozova, Cristina C. Clement, Susmita Kaushik, Barbara Stiller, Esperanza Arias, Atta Ahmad, Jennifer N. Rauch, Victor Chatterjee, Chiara Melis, Brian Scharf, Jason E. Gestwicki, Ana Maria Cuervo, Erik R.P. Zuiderweg, Laura Santambrogio

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


hsc-70 (HSPA8) is a cytosolic molecular chaperone, which plays a central role in cellular proteostasis, including quality control during protein refolding and regulation of protein degradation. hsc-70 is pivotal to the process of macroautophagy, chaperone-mediated autophagy, and endosomal microautophagy. The latter requires hsc-70 interaction with negatively charged phosphatidylserine (PS) at the endosomal limiting membrane. Herein, by combining plasmon resonance, NMR spectroscopy, and amino acid mutagenesis, we mapped the C terminus of the hsc-70 LID domain as the structural interface interacting with endosomal PS, and we estimated an hsc-70/PS equilibrium dissociation constant of 4.7 ± 0.1 μm. This interaction is specific and involves a total of 4-5 lysine residues. Plasmon resonance and NMR results were further experimentally validated by hsc-70 endosomal binding experiments and endosomal microautophagy assays. The discovery of this previously unknown contact surface for hsc-70 in this work elucidates the mechanism of hsc-70 PS/membrane interaction for cytosolic cargo internalization into endosomes.

Original languageEnglish (US)
Pages (from-to)18096-18106
Number of pages11
JournalJournal of Biological Chemistry
Issue number35
StatePublished - Aug 26 2016

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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