Signal processing in bacterial chemotaxis


Novel aspects in bacterial signal processing, adaptation, and termination

Motility and chemotaxis are important determinants of host recognition and association by many pathogenic and beneficial bacteria. Sinorhizobium meliloti and other rhizobia have specifically adapted these systems for survival in the soil and optimal interaction with their hosts. Our overarching goal is to analyze the novel aspects of this early and important step of symbiosis that governs communication between rhizobia and their hosts. At this point, it is not understood how signal adaptation and termination are regulated. The ultimate goal of this project is to determine the reaction mechanisms and cellular stoichiometries of the key players in chemotaxis, which will allow more detailed experimental approaches and theoretical modeling of bacterial chemotaxis in the soil and during host-interaction. This knowledge majorly impacts agricultural and environmental issues by enhancing our understanding of the cues that plant symbionts and pathogens use to interact with their hosts.


T.D. Arapov, Castañeda Saldaña R., Sebastian A.L., Ray W.K., Helm R.F., Scharf B.E. (2020) Cellular stoichiometry of chemotaxis proteins in Sinorhizobium meliloti. Journal of Bacteriology; 202(14), 141-120. (DOI: 10.1128/JB.00141-20)

T.D. Arapov, Kim J., Cronin R.M., Pahima M., Scharf B.E. (2020) Programmed proteolysis of chemotaxis proteins in Sinorhizobium meliloti: Features in the C-terminal region control McpU degradation. Journal of Bacteriology. 202(17), 1-15.  [Selected for the Spotlight Section of the Journal] (

D. Dogra, Purschke F.G., Wagner V., Haslbeck M., Kriehuber T., Hughes J.G., Van Tassell M.L., Gilbert C., Niemeyer M., Ray W.K., Helm R.F., Scharf B.E. (2012) Sinorhizobium meliloti CheA complexed with CheS exhibits enhanced binding to CheY1 resulting in accelerated CheY1-P dephosphorylation. Journal of Bacteriology 194, 1075-1087. [cited in faculty of 1000] (DOI:10.1128/JB.06505-11)

D. Wibberg, Blom J., Winkler A., Albersmeier A., Pühler A., Scharf B.E. (2013) Draft genome sequence of Sinorhizobium meliloti RU11/001, a model organism for flagellum structure, motility and chemotaxis. Journal of Biotechnology 4, 731-733. (DOI:10.1016/j.jbiotec.2013.10.015)

H. Riepl, Maurer T., Kalbitzer H.R., Meier V.M., Schmitt R., Scharf B. (2008) Interaction of CheY2 and CheY2-P with the cognate CheA kinase in the chemosensory-signalling chain of Sinorhizobium meliloti. Molecular Microbiology 69, 1373-1384. (DOI:10.1111/j.1365-2958.2008.06342.x)

H. Riepl, Scharf B., Schmitt R., Maurer T., Kalbitzer H.R. (2004) Solution structures of the inactive and BeF3-activated response regulator CheY2. 338, 287-297. [cited in faculty of 1000] (DOI:10.1016/j.jmb.2004.02.054 )