Date of Award

Spring 2018

Document Type

Thesis

Terms of Use

© 2018 Nicholas E. Petty. All rights reserved. This work is freely available courtesy of the author. It may only be used for non-commercial, educational, and research purposes. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Chemistry & Biochemistry Department

First Advisor

Stephen T. Miller

Abstract

Bacteria were believed to exist as solitary, unicellular organisms until about 50 years ago with the discovery of quorum sensing by John Woodland Hastings. Since then, numerous studies have examined the broad reaching functions controlled by bacterial quorum sensing, including biofilm formation and virulence. Work done by the Bassler laboratory proposed a "universal" quorum sensing pathway that uses a novel signal molecule, autoinducer-2 (AI-2), for intraspecies and interspecies communication. This quorum sensing pathway uses proteins encoded by the lsr operon to uptake and process the AI-2 signaling molecule. This work examines two of these proteins, LsrE and LsrB. LsrE, a putative epimerase, is the final protein in the AI-2 quorum sensing pathway yet to be characterized. Prior attempts at functionality determination through bioassays and crystallographic analysis were unsuccessful. Work herein focused on creating truncations of putatively disordered terminal regions to increase protein stability. In addition to LsrE, this work also focused on the putative AI-2 receptor protein LsrB from T. composti. Prior work with T. composti Lsr B experienced difficulties in functionality assays and crystallographic studies. Here, AI-2 binding is demonstrated using a bioluminescence assay. Binding was further characterized using isothermal titration calorimetry. Finally, an N-terminal truncation of T. composti LsrB was generated to facilitate crystallographic studies to determine structure and binding interactions.

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