Fig. 2

Unfolding of Hsp82 and Hsc82. a Schematic depicting how force is applied across the monomer of Hsc82 or Hsp82 using optical trapping (see Methods for details). b Example unfolding traces of Hsp82 (left) and Hsc82 (right) pulled at a constant velocity of 500 nm/s. The traces are colored according to domain. In both these example traces, the CTD is seen to unfold first (shown in orange), followed by the NTD (blue) and finally, the middle domain (green). c Performing repeated force-extension cycles and recording the unfolding forces and contour length gains for each domain results in the scatter plots shown here. The average unfolding forces and contour length gains for Hsp82 and Hsc82 are the same within error (see Table 1). d Repeated force-extension cycles at 500 nm/s with no waiting time at zero force result in large numbers of force-extension traces that do not show the native unfolding pattern. This occurs as a result of inter- and intra-domain misfolds in the monomers of Hsc82 and Hsp82, which is why misfolds with contour length gains longer than those of natively folded domains are common. Here, native mechanical signatures of individual domains are colored according to the domain (blue for the NTD, green for the middle domain, orange for the CTD), and events which did not match the native unfolding signatures for any domains are shown in red. Hsp82 data (left-hand side) is from 38 force-extension cycles for a single molecule, and Hsp82 data (right-hand side) is from 55 force-extension cycles for a single molecule