Unraveling CheA Regulation by Domain Stabilization in Bacterial Chemotaxis

Presenter

Stanley Yuan

Campus

UMass Amherst

Sponsor

Lynmarie K. Thompson, Department of Chemistry, UMass Amherst

Schedule

Session 5, 3:30 PM - 4:15 PM [Schedule by Time][Poster Grid for Time/Location]

Location

Poster Board A35, Campus Center Auditorium, Row 2 (A21-A40) [Poster Location Map]

Abstract

Motile bacteria utilize chemotaxis signaling complexes to migrate toward favorable conditions. E. coli chemotaxis complexes form hexagonal arrays consisting of transmembrane receptor trimers-of-dimers, a homodimeric histidine kinase CheA bound to the receptor, and a coupling protein CheW that connects the two at the membrane-distal end of the receptor. Ligand binding and changes in methylation of the receptor shift CheA into kinase-on or off signaling outputs that are proposed to be induced via changes in protein dynamics and stability. The methylated (CF4Q) and unmethylated (CF4E) forms of the cytoplasmic fragment of the receptor are used to mimic the kinase-on and off forms in native-like complexes, respectively. Hydrogen deuterium exchange mass spectrometry (HDX-MS) studies revealed destabilization of the P3 dimerization domain of CheA in CF4E complexes. However, it is not clear whether the unmethylated receptors regulated CheA by disrupting P3. We hypothesized that stabilizing the CheA dimer would negate the destabilizing effects caused by CF4E. We introduced a cysteine (V298C) within P3 that can form a disulfide to favor dimerization. Kinase assays are in progress to determine whether the V298C disulfide dimer restores kinase activity in the normally kinase-off CF4E. Overall, this study aims to determine the role of P3 stabilization in regulating CheA signaling to better understand signal transduction using bacterial chemotaxis complexes as a model.

Keywords

Chemotaxis, Kinase, Receptor Array, Signal Transduction, Protein Structure

Research Area

Chemistry and Materials Science

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