Prefoldins in Archaea.

Molecular chaperones promote the correct folding of proteins in aggregation-prone cellular environments by stabilizing nascent polypeptide chains and providing appropriate folding conditions. Prefoldins (PFDs) are molecular chaperones found in archaea and eukaryotes, generally characterized by a unique jellyfish-like hexameric structure consisting of a rigid beta-barrel backbone with protruding flexible coiled-coils. Unlike eukaryotic PFDs that mainly interact with cytoskeletal components, archaeal PFDs can stabilize a wide range of substrates; such versatility reflects PFD's role as a key element in archaeal chaperone systems, which often lack general nascent-chain binding chaperone components such as Hsp70. While archaeal PFDs mainly exist as hexameric complexes, their structural diversity ranges from tetramers to filamentous oligomers. PFDs bind and stabilize nonnative proteins using varying numbers of coiled-coils, and subsequently transfer the substrate to a group II chaperonin (CPN) for refolding. The distinct structure and specific function of archaeal PFDs have been exploited for a broad range of applications in biotechnology; furthermore, a filament-forming variant of PFD has been used to fabricate nanoscale architectures of defined shapes, demonstrating archaeal PFDs' potential applicability in nanotechnology.