title: The physical and functional thermal sensitivity of bacterial chemoreceptors.
abstract: The bacterium Escherichia coli exhibits chemotactic behavior at temperatures ranging from approximately 20 °C to at least 42 °C. This behavior is controlled by clusters of transmembrane chemoreceptors made from trimers of dimers that are linked together by cross-binding to cytoplasmic components. By detecting fluorescence energy transfer between various components of this system, we studied the underlying molecular behavior of these receptors in vivo and throughout their operating temperature range. We reveal a sharp modulation in the conformation of unclustered and clustered receptor trimers and, consequently, in kinase activity output. These modulations occurred at a characteristic temperature that depended on clustering and were lower for receptors at lower adaptational states. However, in the presence of dynamic adaptation, the response of kinase activity to a stimulus was sustained up to 45 °C, but sensitivity notably decreased. Thus, this molecular system exhibits a clear thermal sensitivity that emerges at the level of receptor trimers, but both receptor clustering and adaptation support the overall robust operation of the system at elevated temperatures.
authors: The Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel.
authors: Vered
authors: V
authors: Frank
authors: Moriah
authors: M
authors: Koler
authors: Smadar
authors: S
authors: Furst
authors: Ady
authors: A
authors: Vaknin
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D002628:Chemoreceptor Cells / Q000737:chemistry* / Q000378:metabolism*; D002633:Chemotaxis; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D005453:Fluorescence; D031541:Fluorescence Resonance Energy Transfer; D006358:Hot Temperature; D008164:Luminescent Proteins; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D011487:Protein Conformation; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; C057331:Tar protein, E coli; C054562:yellow fluorescent protein, Bacteria