Fig. 6: Proposed model for CadC activation of the lysine decarboxylation system. | Communications Biology

Fig. 6: Proposed model for CadC activation of the lysine decarboxylation system.

From: Molecular mechanism of proteolytic cleavage-dependent activation of CadC-mediated response to acid in E. coli

Fig. 6

When the pH value is ≥ 7, CadC activity is inhibited by LysP. Conversely, when the pH is < 7 and lysine is present, LysP initiates lysine transport (I). This process concomitantly triggers the opening of the intramolecular disulfide bond in CadC by DsbC (II). The exposed cleavage site allows proteases DegP and DegQ to cleave CadC. This results in the generation of an active N-terminal DNA-binding domain, activating the expression of cadBA. Upon activation, CadA decarboxylates lysine to produce cadaverine, transported extracellularly by CadB. As cadaverine accumulates to a threshold, feedback regulation inhibits the enzymatic digestion activation of CadC, maintaining cellular homeostasis (III).

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