Structural investigation of the molecular chaperonin TF55 from the thermophilic archeon Sulfolobus solfataricus
Chaperonins are ubiquitous multi-subunit macromolecules that mediate the folding and assembly of certain proteins that cannot fold properly in vivo. The Archaea bacterium Sulfolobus solfataricus encodes for three chaperonin complexes formed from three different, but closely related subunits named α, β and γ. These subunits form a homo-18mer composed of all β subunits at temperatures ranging between 80°C-85°C, a hetero-16mer composed of α and β subunits at temperatures ranging between 70°C-75°C and a hetero 18mer composed of α, β and γ subunits at temperatures of 60°C. Structures exist for the chaperonin TF55 all-β complex and for the TF55 αβ complex but not for the TF55 αβγ complex. Here we present the structural investigation of the chaperonin TF55 αβγ in the presence of ATP. The cryo-EM reconstruction of TF55 chaperonin complex revealed a double-ring of 18 subunits with nine subunits in each ring. Each of the subunits are arranged in an alternating fashion where three hetero-trimers reside in each ring and the intact 18-meric complex is formed by two of these rings stacked back to back, similar to other chaperonin complexes.
Molugu, Sanjay Kumar, "Structural investigation of the molecular chaperonin TF55 from the thermophilic archeon Sulfolobus solfataricus" (2014). ETD Collection for University of Texas, El Paso. AAI1583933.