Fibrillar α-synuclein (α-Syn) is the principal component of Lewy bodies, which 
are evident in individuals affected by Parkinson disease (PD). This 
neuropathologic form of α-Syn plays a central role in PD progression as it has 
been shown to propagate between neurons. Tools that interfere with α-Syn 
assembly or change the physicochemical properties of the fibrils have potential 
therapeutic properties as they may be sufficient to interfere with and/or halt 
cell-to-cell transmission and the systematic spread of α-Syn assemblies within 
the central nervous system. Vertebrate molecular chaperones from the 
constitutive/heat-inducible heat shock protein 70 (Hsc/p70) family have been 
shown to hinder the assembly of soluble α-Syn into fibrils and to bind to the 
fibrils and very significantly reduce their toxicity. To understand how Hsc70 
family members sequester soluble α-Syn, we set up experiments to identify the 
molecular chaperone-α-Syn surface interfaces. We cross-linked human Hsc70 and 
its yeast homologue Ssa1p and α-Syn using a chemical cross-linker and mapped the 
Hsc70- and Ssa1p-α-Syn interface. We show that the client binding domain of 
Hsc70 and Ssa1p binds two regions within α-Syn similar to a tweezer, with the 
first spanning residues 10-45 and the second spanning residues 97-102. Our 
findings define what is necessary and sufficient for engineering Hsc70- and 
Ssa1p-derived polypeptide with minichaperone properties with a potential as 
therapeutic agents in Parkinson disease through their ability to affect α-Syn 
assembly and/or toxicity.