Structural and Biological Interaction of hsc-70 Protein with Phosphatidylserine in Endosomal Microautophagy.
J Biol Chem
; 291(35): 18096-106, 2016 08 26.
Article
en En
| MEDLINE
| ID: mdl-27405763
ABSTRACT
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.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Fosfatidilserinas
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Endosomas
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Autofagia
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Proteínas del Choque Térmico HSC70
/
Membranas Intracelulares
Límite:
Animals
Idioma:
En
Revista:
J Biol Chem
Año:
2016
Tipo del documento:
Article