The term amyloid defines a group of proteins that aggregate into plaques or fibers. Amyloid fibers are mostly due to their relation with neurodegenerative diseases in humans, however, amyloid fibers play a functional role when secreted by lower organisms, such as bacteria and fungi. Originating either in humans or in micro-organisms, the sequence of amyloid proteins is decorated with hexapeptides with high propensity to form fibers, known as steric zippers. We have found that steric zippers form globular structures on route to making fibers and exhibit a characteristic force (F)-distance (D) fingerprint when pulled with an AFM tip. Particularly, the F-D pulling curves showed force - plateau steps, suggesting that the globular structures were composed of chains that were unwound like a yarn ball. Force plateau analysis showed that the F-D characteristic parameters were sequence-sensitive, representing differences in the packing of the hexapeptides within the globules. These unprecedented findings show that steric zippers exhibit a characteristic nanomechanical signature in solution, in addition to previously observed characteristic crystallographic structure. Getting to the fundamental interactions that govern the unzipping of full-length amyloid fibers may initiate the development of new anti-amyloid methods that target the physical, in addition to the structural, properties of steric zippers.<br/>

Nanomechanical properties of amyloid steric zipper globular structures

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.