Expression levels of (A) RpaA, (C) RpaB, (E) ManR and Trx in the control E. coli Origami2 strain (Control), the strain expressing only TrxMC35S (Trx), the strain expressing only a TF and the strain expressing both TrxMC35S and a TF were examined. The whole cell extract (C), the soluble fraction (S) and the insoluble pellet fraction (P) were separated by 15% SDS-PAGE and stained with CBB. The interaction of (B) RpaA, (D) RpaB and (F) ManR with Trx was examined by non-reducing 12% SDS-PAGE and immunoblot analysis of soluble proteins from each strain. TFs and Trx were detected using a His-tag antibody and S-protein, respectively. ± indicates with or without 100 mM DTT treatment. Black arrow, white arrow and arrow head indicate the TF monomer, the Trx monomer, and the Trx-TF complex, respectively.