Structure of the molecular chaperone prefoldin: Unique interaction of multiple coiled coil tentacles with unfolded proteins

Prefoldin (GimC) is a hexameric molecular chaperone complex built from two related classes of subunits and present in all eukaryotes and archaea. Pref oldin interacts with nascent polypeptide chains and, in vitro, can function ally substitute for the Hsp70 chaperone system in stabilizing non-native pr oteins for subsequent folding in the central cavity of a chaperonin. Here, we present the crystal structure and characterization of the prefoldin hexa mer from the archaeum Methanobacterium thermoautotrophicum. Prefoldin has t he appearance of a jellyfish: its body consists of a double beta barrel ass embly with six long tentacle-like coiled coils protruding from it. The dist al regions of the coiled coils expose hydrophobic patches and are required for multivalent binding of nonnative proteins.