Ligand affinity and kinase activity are independent of bacterial chemotaxis receptor concentration: insight into signaling mechanisms.

ABSTRACT: Binding of attractant to bacterial chemotaxis receptors initiates a transmembrane signal that inhibits the kinase CheA bound ~300 Å distant at the other end of the receptor. Chemoreceptors form large clusters in many bacterial species, and the extent of clustering has been reported to vary with signaling state. To test whether ligand binding regulates kinase activity by modulating a clustering equilibrium, we measured the effects of two-dimensional receptor concentration on kinase activity in proteoliposomes containing the purified Escherichia coli serine receptor reconstituted into vesicles over a range of lipid:protein molar ratios. The IC(50) of kinase inhibition was unchanged despite a 10-fold change in receptor concentration. Such a change in concentration would have produced a measur

SUBMITTER: Sferdean FC 

PROVIDER: S-EPMC3611967 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature