X-ray and electron microscopy techniques help unfold the story of protein chaperones.

A combination of X-ray crystallography and cryo- (cryo-EM) assisted in a collaborative effort to obtain the highest-resolution of the fungal protein Hsp104, which may serve to hinder the formation of certain degenerative diseases. The team, whose members included researchers from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, also verified a helical structure for the protein-formed hexamers, once believed flat. The results were published online in the Dec. 27, 2018 issue of Structure.

Hsp104 is a hexameric AAA+ protein known as a chaperone, which helps in the natural folding processes of proteins for proper cell function. More importantly, perhaps, this class of hexamers can repair misfolded or aggregated proteins that can lead to protein-caused abnormalities like neurodegeneration.

Variants of these chaperones are common among multicellular organisms, but Hsp104 has no homologue among humans and other animals. While it is more robust than human-derived chaperones that can fail under cellular stress, Hsp104 has been observed folding human proteins.

“We did some experiments where we expressed human proteins in yeast, which makes the yeast sick because they aggregate. But if you express Hsp104, the one from the fungus Calcarisporiella thermophila, it protects the yeast from this aggregation disease,” said Argonne Distinguished FellowAndrzej Joachimiak.

Read more at: Phys.org