1. The disorderly conduct of Hsc70 and its interaction with the Alzheimer's-related Tau protein
- Author
-
Taylor, Isabelle R, Ahmad, Atta, Wu, Taia, Nordhues, Bryce A, Bhullar, Anup, Gestwicki, Jason E, and Zuiderweg, Erik RP
- Subjects
Biochemistry and Cell Biology ,Biological Sciences ,Alzheimer's Disease ,Neurodegenerative ,Acquired Cognitive Impairment ,Dementia ,Alzheimer's Disease including Alzheimer's Disease Related Dementias (AD/ADRD) ,Aging ,Brain Disorders ,1.1 Normal biological development and functioning ,Underpinning research ,Aetiology ,2.1 Biological and endogenous factors ,Generic health relevance ,Adenosine Triphosphate ,Alzheimer Disease ,Binding Sites ,Crystallography ,X-Ray ,HSC70 Heat-Shock Proteins ,Humans ,Protein Binding ,Protein Conformation ,Protein Folding ,Protein Interaction Domains and Motifs ,tau Proteins ,chaperone ,microtubule-associated protein ,protein conformation ,protein complex ,nuclear magnetic resonance ,Chemical Sciences ,Medical and Health Sciences ,Biochemistry & Molecular Biology ,Biological sciences ,Biomedical and clinical sciences ,Chemical sciences - Abstract
Hsp70 chaperones bind to various protein substrates for folding, trafficking, and degradation. Considerable structural information is available about how prokaryotic Hsp70 (DnaK) binds substrates, but less is known about mammalian Hsp70s, of which there are 13 isoforms encoded in the human genome. Here, we report the interaction between the human Hsp70 isoform heat shock cognate 71-kDa protein (Hsc70 or HSPA8) and peptides derived from the microtubule-associated protein Tau, which is linked to Alzheimer's disease. For structural studies, we used an Hsc70 construct (called BETA) comprising the substrate-binding domain but lacking the lid. Importantly, we found that truncating the lid does not significantly impair Hsc70's chaperone activity or allostery in vitro Using NMR, we show that BETA is partially dynamically disordered in the absence of substrate and that binding of the Tau sequence GKVQIINKKG (with a KD = 500 nm) causes dramatic rigidification of BETA. NOE distance measurements revealed that Tau binds to the canonical substrate-binding cleft, similar to the binding observed with DnaK. To further develop BETA as a tool for studying Hsc70 interactions, we also measured BETA binding in NMR and fluorescent competition assays to peptides derived from huntingtin, insulin, a second Tau-recognition sequence, and a KFERQ-like sequence linked to chaperone-mediated autophagy. We found that the insulin C-peptide binds BETA with high affinity (KD < 100 nm), whereas the others do not (KD > 100 μm). Together, our findings reveal several similarities and differences in how prokaryotic and mammalian Hsp70 isoforms interact with different substrate peptides.
- Published
- 2018