Institute for Microbiology and Wine Research, Johannes Gutenberg University, D-55099 Mainz, Germany.
Biol Chem. 2012 Nov;393(11):1291-7. doi: 10.1515/hsz-2012-0229.
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. Phosphorylated DcuR induces the expression of the target genes. Sensing by DcuS requires the presence of the C(4)-dicarboxylate transporter DctA during aerobic growth. DctA forms a sensor unit with DcuS, and a short C-terminal sequence of DctA forming the putative helix 8b is required for interaction with DcuS. Helix 8b contains a LDXXXLXXXL motif that is essential for function and interaction. DcuS requires the PAS(C) domain for signal perception from DctA. Thus, DcuS and DctA form a DctA/DcuS sensory unit, and DcuS perceives stimuli from two different sites (PAS(P) and DctA). The signal transfer pathways are supposed to merge at PAS(C). The fumarate/succinate antiporter DcuB takes over the role as a co-sensor of DcuS under anaerobic growth conditions.
大肠杆菌的膜整合传感器激酶 DcuS 由位于周质的感应 PAS(P)结构域、跨膜螺旋 TM1 和 TM2、细胞质 PAS(C)结构域和激酶结构域组成。刺激物（C(4)-二羧酸）在 PAS(P)上的结合对于刺激激酶结构域的磷酸化是必需的，导致磷酸基团转移到响应调节剂 DcuR。PAS(C)作为信号装置或信号从 TM2 到激酶的传递中的中继起作用。磷酸化的 DcuR 诱导靶基因的表达。在有氧生长期间，DcuS 的感应需要 C(4)-二羧酸转运蛋白 DctA 的存在。DctA 与 DcuS 形成传感器单元，并且 DctA 形成假定的螺旋 8b 的短 C 末端序列对于与 DcuS 的相互作用是必需的。螺旋 8b 包含一个 LDXXXLXXXL 基序，该基序对于功能和相互作用是必需的。DcuS 需要 PAS(C)结构域才能从 DctA 感知信号。因此，DcuS 和 DctA 形成 DctA/DcuS 感觉单元，并且 DcuS 从两个不同的位点（PAS(P)和 DctA）感知刺激。信号传递途径应该在 PAS(C)处融合。在厌氧生长条件下，富马酸/琥珀酸反向转运蛋白 DcuB 取代 DcuS 的共传感器作用。
