Conversion of the sensor kinase DcuS of Escherichia coli of the DcuB/DcuS sensor complex to the C -dicarboxylate responsive form by the transporter DcuB.

The sensor kinase DcuS of Escherichia coli co-operates under aerobic conditions with the C -dicarboxylate transporter DctA to form the DctA/DcuS sensor complex. Under anaerobic conditions C -dicarboxylate transport in fumarate respiration is catalyzed by C -dicarboxylate/fumarate antiporter DcuB. (i) DcuB interacted with DcuS as demonstrated by a bacterial two-hybrid system (BACTH) and by co-chromatography of the solubilized membrane-proteins (mHPINE assay).

Transmembrane signaling in the sensor kinase DcuS of Escherichia coli: A long-range piston-type displacement of transmembrane helix 2.

The C4-dicarboxylate sensor kinase DcuS is membrane integral because of the transmembrane (TM) helices TM1 and TM2. Fumarate-induced movement of the helices was probed in vivo by Cys accessibility scanning at the membrane-water interfaces after activation of DcuS by fumarate at the periplasmic binding site. TM1 was inserted with amino acid residues 21-41 in the membrane in both the fumarate-activated (ON) and inactive (OFF) states.

The cytoplasmic PASC domain of the sensor kinase DcuS of Escherichia coli: role in signal transduction, dimer formation, and DctA interaction.

The cytoplasmic PASC domain of the fumarate responsive sensor kinase DcuS of Escherichia coli links the transmembrane to the kinase domain. PASC is also required for interaction with the transporter DctA serving as a cosensor of DcuS. Earlier studies suggested that PASC functions as a hinge and transmits the signal to the kinase.

The sensor kinase DcuS of Escherichia coli: two stimulus input sites and a merged signal pathway in the DctA/DcuS sensor unit.

The membrane-integral sensor kinase DcuS of Escherichia coli consists of a periplasmically located sensory PAS(P) domain, transmembrane helices TM1 and TM2, a cytoplasmic PAS(C) domain and the kinase domain. Stimulus (C(4)-dicarboxylate) binding at PAS(P) is required to stimulate phosphorylation of the kinase domain, resulting in phosphoryl transfer to the response regulator DcuR. PAS(C) functions as a signaling device or a relay in signal transfer from TM2 to the kinase.