eCommons

 

Single-molecule Studies of Multicomponent Efflux Complexes and Metal-responsive Regulators in Live Bacteria

Other Titles

Abstract

This dissertation has two chapters and two appendices: Chapters 1-2 are published research, and Appendices 1-2 are research in progress. Chapter 1 focuses on biomechanical manipulations of the multicomponent efflux complex, CusCBA, a system used by E. coli to resist copper and silver toxicity. Here, I collaborated with colleagues in Cornell’s mechanical engineering department to investigate the role of mechanical forces on the function of protein complexes that span the envelope of Gram-negative cells. We found that mechanical stress promotes disassembly of the CusCBA complex in E. coli and, as a result, renders bacteria more susceptible to metal toxicity. I performed single-molecule imaging experiments and cell-growth assays, analyzed the data, and wrote the paper, which resulted in a co-first authored publication (Proc. Natl. Acad. Sci. U.S.A. 2019, 116, 25462-25467). Chapter 2 focuses on the two-component regulatory system, CusRS. Here, I collaborated with two post-docs in the Chen Lab to elucidate the mechanism by which sensor CusS interacts with response regulator CusR to aid in E. coli’s metal detoxification. From live cell single-molecule imaging experiments, we determined the timepoint in which CusS-CusR interaction affinity switches on (i.e., after CusS senses its metal substrate) and discovered a substrate-sensing_induced mobilization of CusS. I designed and constructed cell strains, performed biochemical experiments, and helped write the manuscript, in which I am a co-first author (Proc. Natl. Acad. Sci. U.S.A. 2020, 117, doi: 10.1073/pnas.1919816117). The introductions of Appendices 1-2 are patterned from the proposals of Prof. Peng Chen; the rest of these chapters detail my molecular biology progress for these projects. Appendix 1 focuses on a novel bottom-up microbiome approach to understand microbial community and cell-cell interactions in bacterial metal homeostasis. We seek to understand how individual E. coli cells communicate with one another in the context of zinc uptake and efflux and how this communication can be regulated in a cell community under changing zinc environments. Appendix 2 focuses on the tripartite efflux complex EmrAB-TolC, which protects E. coli from ionophores and antibiotics. We plan to elucidate the assembly mechanism of EmrAB-TolC, as well as its substrate-responsive element, to determine whether there are parallels between this system and CusCBA, in which we discovered an adaptor-protein_mediated dynamic pump assembly.

Journal / Series

Volume & Issue

Description

317 pages

Sponsorship

Date Issued

2020-08

Publisher

Keywords

Location

Effective Date

Expiration Date

Sector

Employer

Union

Union Local

NAICS

Number of Workers

Committee Chair

Chen, Peng

Committee Co-Chair

Committee Member

Hernandez, Christopher J.
Lin, Hening

Degree Discipline

Chemistry and Chemical Biology

Degree Name

Ph. D., Chemistry and Chemical Biology

Degree Level

Doctor of Philosophy

Related Version

Related DOI

Related To

Related Part

Based on Related Item

Has Other Format(s)

Part of Related Item

Related To

Related Publication(s)

Link(s) to Related Publication(s)

References

Link(s) to Reference(s)

Previously Published As

Government Document

ISBN

ISMN

ISSN

Other Identifiers

Rights

Rights URI

Types

dissertation or thesis

Accessibility Feature

Accessibility Hazard

Accessibility Summary

Link(s) to Catalog Record