Figure 1.

Co‐translational expression of FPs in the periplasm. FP fusions were expressed in the periplasm and attached to the periplasmic (Peri) side of the inner membrane (IM) through PBP5 (encoded by dacA). The DsbA (dsba^ss) signal sequence is a substrate for the signal recognition particle (SRP) that directs co‐translational transport through the SecYEG translocase of the N‐terminal fused gene product translated in the cytoplasm (Cyto). The FP fusion is translocated to the periplasm and the signal sequence is cleaved off. Here the FP is exposed to periplasmic conditions under which it needs to efficiently fold its ß‐barrel and subsequently mature its chromophore to become fluorescent. FPs that are unable to fluoresce in the periplasm thus have problems with either folding or chromophore maturation.