Predicted structures and hexameric models of Hsp104 and ClpB
(a) Domain organization of one monomer of Hsp104 and ClpB. N-terminal domain (N) shown in purple, Nucleotide binding domain 1 (NBD1) shown in cyan, Middle domain (MD) in yellow, Nucleotide binding domain 2 (NBD2) in dark blue. Only Hsp104 has the short C-terminal extension (C) shown in green. Sequence numbering for ClpB is shown on top and for Hsp104 is shown on the bottom. (b) TClpB crystal structure. Domain coloring corresponds with part (a). A 180° rotation about the vertical axis is shown on the right. (c) The Tsai model for the hexameric quaternary structure of TClpB. The Tsai model, which was initially based on Cryo-EM envelopes generated with TClpB is shown on left. (d) The Saibil model, which used Hsp104 to generate Cryo-EM density, is shown in the middle. (e) The 6.93Å crystal structure of hexameric, full length ClpC is shown on the right. The adaptor protein MecA was omitted for clarity. A side view is shown on top and a view down the axial channel from the N-terminus is shown on the bottom. One subunit is colored as described in part (a). The other five subunits are in gray.