Composition and function of the DctA/DcuS sensor complex of E. coli
Final Report Abstract
Sensing of C4-DC by the DcuS-DcuR two-component system is remarkably complex and includes far-reaching complex formation by the sensors system. Function of DcuS requires interaction with transporters that convert DcuS to the sensory competent state. Under anaerobic conditions transporter DcuB serves as co-regulator, under aerobic conditions transporter DctA. The DctA-DcuS complex additionally interacts with the transporter DauA. The transporters, however, are not required for sensing which resides only in DcuS. The transporters DcuB and DctA rather convert DcuS to the C4-DC responsive state, whereas the role of DauA is obscure. The bacteria contain low levels of free (not-complexed) DcuSF. DcuSF is in the permanent active state and ensures basal level of DcuB synthesis in the absence of C4-DCs. DcuS forms a stable complex with DcuR with DcuR in vivo and in vitro which is further stabilized by phosphorylation of DcuS and of DcuR . Overall, the data imply that sensing by the DcuS-DcuR system is complex and requires complex formation with co-regulators representing transport proteins (DcuB, DctA, DauA). The mechanism behind the conversion of DcuS by the transporters to the C4-DC responsive state is still under study. Also, the physiological significance of co-regulation by the transport proteins has not become clear in all details. The closely related DcuA transporter that is a member of the Dcu family of transporters has no function in co-regulation of DcuS. DcuA functions as a L-aspartate/fumarate antiport and serves as a nitrogen shuttle for the net uptake of nitrogen (without net uptake of carbon).
Publications
- (2016) Conversion of the sensor kinase DcuS of Escherichia coli of the DcuB/DcuS sensor complex to the C4-dicarboxylate responsive form by the transporter DcuB. Environ Microbiol
Wörner S, Strecker, A, Monzel C, Zeltner M, Witan J, Ebert-Jung, A, Unden G
(See online at https://doi.org/10.1111/1462-2920.13418) - (2016) Cooperation of secondary transporters and sensor kinases in transmembrane signalling: The DctA/DcuS and DcuB/DcuS sensor complexes of E. coli. Advances Bact Physiol 68: 139-167
Unden G, Wörner S, Monzel C
(See online at https://doi.org/10.1016/bs.ampbs.2016.02.003) - (2017) The E. coli dicarboxylic acid transporter DauA acts as a signal transducer by interacting with the DctA uptake system. Sci Rep 7: 16331
Karinou E, Hoskisson PA, Strecker A, Unden G, Javelle A
(See online at https://doi.org/10.1038/s41598-017-16578-w) - (2018) Cellular concentrations of the transporters DctA, DcuB, and the sensor DcuS of E. coli and the contributions of free and complexed DcuS to transcriptional regulation by DcuR. J Bacteriol.
Wörner S, Surmann K, Ebert-Jung A, Völker U, Hammer E, Unden G
(See online at https://doi.org/10.1128/JB.00612-17) - (2018) DcuA of aerobically grown E. coli serves as a nitrogen shuttle (L-aspartate/fumarate) for nitrogen uptake. Molec Microbiol.
Strecker A, Schubert Ch, Zedler S, Steinmetz P, Unden G
(See online at https://doi.org/10.1111/mmi.14074)
