TRANSCRIPTIONAL REGULATION OF THE CHEMORECEPTOR GENES AND FORMATION OF RECEPTOR CLUSTERS IN LATERAL MEMBRANE REGIONS OF ESCHERICHIA COLI CELLS

In Escherichia coli, the genes encoding chemoreceptors, including Tsr for serine and Tar for aspartate, belong to the flagellar regulon, and their transcription is under the control of the sigma factor FliA. Previous studies identified the pyruvate-responding global transcription factor PdhR binds to the tsr and tar promoters. In this study, I examined how PdhR regulates these promoters using strains expressing Tar and Tsr fused to fluorescent proteins from the native promoters and found that PdhR acts as a positive regulator for both of the promoters. I also intended to unravel cluster formations of the chemoreceptors before they form a huge cluster at a cell pole. Single molecule imaging revealed that the Tar and Tsr form mixed clusters of variable sizes together with low-abundance chemoreceptors in the lateral region of the cytoplasmic membrane