Heterologous Expression ofPseudomonas putidaMethyl-Accepting Chemotaxis Proteins YieldsEscherichia coliCells Chemotactic to Aromatic Compounds
ABSTRACTEscherichia coli, commonly used in chemotaxis studies, is attracted mostly by amino acids, sugars, and peptides. We envisioned modifying the chemotaxis specificity ofE. coliby expressing heterologous chemoreceptors fromPseudomonas putidaenabling attraction either to toluene or benzoate. ThemcpTgene encoding the type 40-helical bundle (40H) methyl-accepting chemoreceptor for toluene fromPseudomonas putidaMT53 and thepcaYgene for the type 40H receptor for benzoate and related molecules fromP. putidaF1 were expressed from thetrgpromoter on a plasmid in motile wild-typeE. coliMG1655.E. colicells expressing McpT accumulated in chemoattraction assays to sources with 60 to 200 μM toluene, although less strongly than the response to 100 μM serine, but statistically significantly stronger than that to sources without any added attractant. An McpT-mCherry fusion protein was detectably expressed inE. coliand yielded weak but distinguishable membranes and polar foci in 1% of cells.E. colicells expressing PcaY showed weak attraction to 0.1 to 1 mM benzoate, but 50 to 70% of cells localized the PcaY-mCherry fusion to their membrane. We conclude that implementing heterologous receptors in theE. colichemotaxis network is possible and, upon improvement of the compatibility of the type 40H chemoreceptors, may bear interest for biosensing.IMPORTANCEBacterial chemotaxis might be harnessed for the development of rapid biosensors, in which chemical availability is deduced from cell accumulation to chemoattractants over time. Chemotaxis ofEscherichia colihas been well studied, but the bacterium is not attracted to chemicals of environmental concern, such as aromatic solvents. We show here that heterologous chemoreceptors for aromatic compounds fromPseudomonas putidaat least partly functionally complement theE. colichemotaxis network, yielding cells attracted to toluene or benzoate. Complementation was still inferior to native chemoattractants, like serine, but our study demonstrates the potential for obtaining selective sensing for aromatic compounds inE. coli.