TY - JOUR T1 - Structural Analysis of a Filamentous Chaperonin from <em>Sulfolobus solfataricus</em> JF - bioRxiv DO - 10.1101/2020.01.13.905216 SP - 2020.01.13.905216 AU - Yi C. Zeng AU - Meghna Sobti AU - Alastair G. Stewart Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/01/14/2020.01.13.905216.abstract N2 - Chaperonins are biomolecular complexes that assist protein folding. Thermophilic Factor 55 (TF55) is a group II chaperonin found in the archaeal genus Sulfolobus and which undergoes changes in modular subunit composition in a temperature-dependent manner. TF55 can form filamentous assemblies that may be a component of the archaeal cytoskeleton or sequester inactive chaperonin. Using cryo-electron microscopy, we have determined the structure of the β-only complex of S. solfataricus TF55 complexes to 3.6 Å resolution and its filamentous form to 5.2 Å resolution. Filament formation can be induced when the protein is enriched in solution or in the presence of the detergent dodecyl maltoside. Helical protrusions in the apical domain facilitate end-on-end interactions in the filamentous state. Our findings establish the molecular basis for forming chaperonin filaments in Sulfolobus and may suggest how filament formation could function as a cold-shock response and provides a background for generating tuneable protein nanowires. ER -