D. proOmpA translocation ATPase activity stimulation of SecA (as in C) in the absence or presence of TF2 or/and SecB4, added at the indicated molar excess over proOmpA1. The T/M ratios were calculated; the one in the absence of chaperones was considered as 100%, all other values were expressed as % of this. n= 2-4 biological replicates. Mean values (± SEM) shown. Unpaired parametric t-test, 95% confidence interval: ns: not significant (p = 0.1032); ****: p < 0.0001; **: p = 0.0037. 