Biochemistry Seminar: Lynmarie Thompson, Univ. of Mass. Amherst
Wed, May 14
12:00 PM — 1:00 PM
MarshakCity College of New York160 Convent Ave
Marshak, MR 1027
Lynmarie Thompson, "Mechanisms of Transmembrane Signaling by Chemotaxis Receptors"Lynmarie Thompson, Assoc Prof., Dept of Chem; Director, Chemistry-Biology Interface Prog., Univ. of Mass. Amherst, "Mechanisms of Transmembrane Signaling by Chemotaxis Receptors: Structure and Dynamics by NMR & HDX-MS"
Bacterial chemotaxis receptors are an excellent system for investigating the mechanism of transmembrane signaling, one of many key life processes mediated by membrane proteins. These receptors, which provide the sensory input needed to direct swimming towards favorable environments, operate in the cell in extended arrays of complexes with the CheA kinase and the CheW coupling protein. It is widely accepted that the signaling mechanism begins with a ligand-induced ~ 2Å piston motion of an alpha helix in the periplasmic and transmembrane domains of the receptor, but it is unclear how the signal is then propagated through the cytoplasmic domain to control the activity of CheA bound ~ 200 Å away. We are assembling native-like functional arrays of complexes of a receptor cytoplasmic fragment (CF), CheA, and CheW for measurements of the differences in conformation and dynamics between the kinase-activating and kinase-inhibited signaling states of the receptor, to gain insight into the mechanism of transmembrane signaling. We have used site-directed solid-state NMR distance measurements to test structural models of the functional receptor. Two-dimensional NMR of uniformly 13C & 15N labeled CF in functional arrays is providing an overview of its structure and dynamics, and setting the stage for interface-directed experiments to measure structural differences between signaling states. Finally, a novel hydrogen exchange mass spectrometry approach is revealing that the major signaling-associated changes in dynamics localize to key regions of the receptor involved in the excitation and adaptation responses.