||Bacteria Escherichia coli
||Sourjik V, Berg HC. Binding of the Escherichia coli response regulator CheY to its target measured in vivo by fluorescence resonance energy transfer. Proc Natl Acad Sci U S A. 2002 Oct 1 99(20):12669-74. p.12669 right column top paragraphPubMed ID12232047
||P.12669 left column bottom paragraph: "To learn more about the binding of CheY∼P to FliM and about the kinetics of the chemotactic response, [investigators] extended [their] recent analysis of phosphorylation-dependent interactions of CheY with CheZ (ref 9) and measured fluorescence resonance energy transfer (FRET) between cyan fluorescent protein (CFP) fused to the N terminus of FliM (CFP-FliM) and yellow fluorescent protein (YFP) fused to the C terminus of CheY (CheY-YFP). The FRET technique relies on the distance-dependent transfer of energy from an excited donor fluorophore (CFP) to an acceptor fluorophore (YFP) and allows one to monitor changes in protein interactions in real time in vivo (refs 10, 11)."
||P.12669 right column top paragraph: "[Investigators] found that CheY∼P binds to FliM in vivo with a dissociation constant of about 3.7 μM, close to the concentration of CheY∼P required for a half-maximal motor response (Cluzel et al., 2000 PMID 10698740 [ref 8]). This binding was much less cooperative than motor switching. The kinetics of CheY∼P binding to FliM was studied following flash release of caged attractant (aspartate) or repellent (protons), and the observed responses were modeled. Rates of the various reactions appear to be optimized for the time scale set by diffusion of CheY∼P through the cytoplasm."