Figure 7From: A tyrosine phosphorylation switch controls the interaction between the transmembrane modulator protein Wzd and the tyrosine kinase Wze of Lactobacillus rhamnosus Model proposed for the tyrosine switch controlling EPS polymerization and attachment. 1. Non-phosphorylated Wzd and Wze interact by forming a complex leading to release of EPS (+) rather than attachment (−). 2. In the presence of ATP, Wze phosphorylates Wzd, allowing chain elongation by the polymerase (+). This phosphorylation of Wzd destabilizes the protein interaction with Wze, allowing Wze to either bind with other non-phosphorylated Wzd proteins, or undergo auto- or trans-transphosphorylation. 3. A transitory interaction between phosphor-rylated Wzd and Wze in the presence of ATP is necessary for the phosphorylation of Wze, possibly allowing the attachment of polysaccharide to the cell wall (+). Phosphatase activity of Wzb for dephosphorylating Wzd and Wze would return the cycle to the non-phosphorylated Wzd/Wze complex that allows release of polysaccharide polymers (+). Question marks indicate proposed steps.Back to article page