DNA-Mediated Assembly of Functional Chemoreceptor Complexes

Presenter: Valerie Chung

Faculty Sponsor: Lynmarie K. Thompson

School: UMass Amherst

Research Area: Biochemistry and Molecular Biology

Session: Poster Session 6, 4:15 PM - 5:00 PM, Auditorium, A60

ABSTRACT

Chemotaxis is the ability of bacteria to detect and respond to chemical gradients in the environment. This helps bacteria such as E. coli swim towards attractants, like sugar and nutrients, and away from repellents. E. coli sense these substances through chemoreceptor complexes, which are arranged in large arrays of three proteins: the chemoreceptor, a kinase CheA, and a coupling protein CheW. Signals from the chemoreceptors trigger a kinase cascade, which controls the flagellar motors. Several techniques are available to assemble these arrays in vitro, but these methods do not control the receptor positioning or the size of the array formed. In this project, DNA scaffolding is used to assemble chemoreceptor arrays to achieve more precise control of protein positions and array size. This control will enable further study of the signaling mechanism. For example, assembly of core signaling complexes containing specific combinations of the methylated and unmethylated receptors (eg. all homodimers or all heterodimers) would provide information on how methylation controls signaling. Assembly of a core signaling unit rather than arrays of a range of sizes would enable single particle cryogenic electron microscopy to achieve higher resolution and reveal the differences between on and off signaling states. A better understanding and control of the chemoreceptor arrays has potential applications, such as drug delivery using bacteria and identifying targets for novel antibiotics. 

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