An order of addition experiment. Luciferase (1.5 μM) was denatured in the presence of IbpA (3 μM) and IbpB (7 μM), diluted to 40 nM and incubated first for 20 min with the components listed in the legend and then complemented with the missing components of the functional ClpB‐KJE bichaperone system. The DnaK, DnaJ, GrpE, ClpB concentrations used were as follows: 1, 0.3, 0.3 and 1.5 μM. Data are the mean ± SD of three independent experiments.