title: Structural and Biological Interaction of hsc-70 Protein with Phosphatidylserine in Endosomal Microautophagy.
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.
authors.affiliation: From the Departments of Pathology and.
authors.forename: Kateryna
authors.initials: K
authors.lastname: Morozova
authors.affiliation: From the Departments of Pathology and.
authors.forename: Cristina C
authors.initials: CC
authors.lastname: Clement
authors.affiliation: Developmental Molecular Biology, Albert Einstein College of Medicine, New York, New York 10461.
authors.forename: Susmita
authors.initials: S
authors.lastname: Kaushik
authors.affiliation: Developmental Molecular Biology, Albert Einstein College of Medicine, New York, New York 10461.
authors.forename: Barbara
authors.initials: B
authors.lastname: Stiller
authors.affiliation: Developmental Molecular Biology, Albert Einstein College of Medicine, New York, New York 10461.
authors.forename: Esperanza
authors.initials: E
authors.lastname: Arias
authors.affiliation: the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48105, and.
authors.forename: Atta
authors.initials: A
authors.lastname: Ahmad
authors.affiliation: the Department of Pharmaceutical Chemistry, University of California at San Francisco, San Francisco, California 94158.
authors.forename: Jennifer N
authors.initials: JN
authors.lastname: Rauch
authors.affiliation: From the Departments of Pathology and.
authors.forename: Victor
authors.initials: V
authors.lastname: Chatterjee
authors.affiliation: From the Departments of Pathology and.
authors.forename: Chiara
authors.initials: C
authors.lastname: Melis
authors.affiliation: From the Departments of Pathology and.
authors.forename: Brian
authors.initials: B
authors.lastname: Scharf
authors.affiliation: the Department of Pharmaceutical Chemistry, University of California at San Francisco, San Francisco, California 94158.
authors.forename: Jason E
authors.initials: JE
authors.lastname: Gestwicki
authors.affiliation: Developmental Molecular Biology, Albert Einstein College of Medicine, New York, New York 10461.
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Cuervo
authors.affiliation: the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48105, and zuiderwe@umich.edu.
authors.forename: Erik R P
authors.initials: ER
authors.lastname: Zuiderweg
authors.affiliation: From the Departments of Pathology and laura.santambrogio@einstein.yu.edu.
authors.forename: Laura
authors.initials: L
authors.lastname: Santambrogio
mesh_terms: D000818:Animals; D001343:Autophagy / Q000502:physiology*; D002460:Cell Line; D011992:Endosomes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050883:HSC70 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007425:Intracellular Membranes / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D010718:Phosphatidylserines / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D050883:HSC70 Heat-Shock Proteins; C494372:Hspa8 protein, mouse; D010718:Phosphatidylserines
keywords: 70-kilodalton heat shock protein (Hsp70); autophagy; chaperone; endosome; phosphatidylserine