Skip to main content
Fig. 3 | Journal of Biological Engineering

Fig. 3

From: Employing aromatic tuning to modulate output from two-component signaling circuits

Fig. 3

The chemotactic circuit underlying control of flagellar rotation. a In the absence of chemoeffectors, baseline CheA activity maintains phsopho-CheY levels that produce the three-dimensional random walk underlying canonical bacterial chemotaxis. b Binding of attractant (red oval in the periplasm; peri) to the chemoreceptor, i.e., aspartate to Tar, abolishes CheA activity, thereby decreasing intracellular phospho-CheY levels. This also results in reduced methylesterase activity due to reduced CheB-P levels. Transmembrane communication (across the black line) is believed to occur via a piston-type displacement of TM2 toward the cytoplasm (cyto; center panel). c Adaptive methylation (blue dots in the cytoplasm) due to reduced CheB-P levels, restores the ability of the chemoreceptor to stimulate CheA activity when it is occupied by an attractant ligand [23]. In summary, this circuit was an excellent initial target for aromatic tuning because binding of attractant leads to displacement of TM2 toward the cytoplasm, reduced CheA kinase activity and increased levels of covalent modification. Conversely, displacements of TM2 toward the periplasm are consistent with increased CheA activity and reduced levels of covalent modification. In addition, signal output from Tar that is biased beyond the compensatory extent of methylation can be detected by monitoring rotation of individual flagella

Back to article page