Figure 1. Schematic outline of the ribose-binding protein based reporter signaling chain.

(a) Ribose-binding protein (RBP) captures its ligand, leading to a conformational change. Ribose-RBP binds the TrzI hybrid transmembrane receptor, which causes a phosphorylation cascade leading to OmpR ~ P binding the ompC-promoter and consecutive gfpmut2 expression. (b) Relevant plasmid constructions. rbsB or tnt.R3 with original rbsB periplasmic export signal sequence and 3′-hexahistidine tag under transcriptional control of the weak constitutive P_AA promoter²⁹. Plasmid pSYK1 with gfpmut2 under the ompC promoter control and trzI under control of P_tac (note that pSYK1 carries the lacI^q gene).