Figure 2. Summary of glucose transport in Salmonella [49].

Glucose can be taken up by the EII^Glc and/or the EII^Man transporters and simultaneously phosphorylated to generate glucose-6-phosphate. The EII^Glc PTS transporter is encoded by two genes; crr encodes the IIA^Glc protein whilst ptsG encodes the membrane-bound IIBC^Glc protein. The EII^Man PTS transporter is encoded by three genes, manX, manY and manZ that encode the IIAB^Man, and the IIC^Man and IID^Man components of the transporter system, respectively. In order to transport and phosphorylate glucose, the EII^Glc and EII^Man transporters require phosphate donated from phosphoenol-pyruvate (PEP) via the EI and HPr phospho-relay proteins that are encoded by ptsI and ptsH, respectively. In addition, unphosphorylated glucose can be imported by the GalP and/or MglABC transporters then subsequently phosphorylated by glucose kinase (Glk) to produce glucose-6-phosphate.