Figure 6: Folding and misfolding pathways of unfolded I27 domains in the absence of chaperones, in the presence of DnaJ and in the presence of DnaJ and DnaK.
From: Action of the Hsp70 chaperone system observed with single proteins
(a) In the absence of chaperones, mechanically unfolded I27 domains (black curved line) can fold (white squares), remain unfolded (filled black circles), or aggregate and misfold (grey symbol). (b) In the presence of DnaJ, the conformational space of unfolded I27 is constrained. This constraint restricts the misfolding pathway and increases the probability for I27 domains to fold. (c) When DnaJ synergizes with DnaK in the presence of ATP, unfolded substrates are constrained and sequestered, thus stabilizing unfolded substrates to be processed. Accordingly, I27 can adopt the unfolded or the folded state, the latter representing the more stable conformer. Values presented were obtained from steady-state refolding experiments (tr=5 s) conducted in the absence of chaperones (a), the presence of 10 μM DnaJ (b) and in the presence of a 1:2 ratio of DnaJ/DnaK (5 μM DnaJ and 10 μM DnaK; c). The thickness of an arrow scales roughly to the probability of the conformational transition.
