Molecular Mechanisms of Copper Homeostasis in Gram-negative Bacteria

Persistent Link:
http://hdl.handle.net/10150/320968
Title:
Molecular Mechanisms of Copper Homeostasis in Gram-negative Bacteria
Author:
George Thompson, Alayna Michelle
Issue Date:
2014
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Embargo:
Release 2-May-2015
Abstract:
Copper is a trace element utilized by organisms as a cofactor involved in redox chemistry, electron transport, photosynthesis, and oxidation reactions. In excess, copper is toxic; it can generate reactive oxygen species causing cellular damage, or poison other metalloproteins by replacing native metal cofactors. Gram-negative bacteria have developed homeostatic mechanisms to maintain the intracellular copper concentration in the face of changing environmental conditions. For Gram-negative enteric bacteria, like Esherichiacoli and Salmonella enterica serovar typhimurium, copper is encountered in industrial and institutional settings, where the metal is used as a broad-spectrum biocide. For environmental bacteria, such as the marine cyanobacterium Synechococcus sp. WH8102, copper stress occurs because human activity changes the concentration of copper in the ocean. This dissertation contains six chapters, relating four stories of our investigations into the molecular mechanisms of copper homeostasis in Gram-negative bacteria. Chapter I contains literature review and background on the implications of bacterial copper homeostasis. Chapter II reports our work investigating the expression of two E. coli proteins, CusF and CusB, upon copper stress; we show that CusF expresses at a ~10-fold molar excess over CusB. Chapter III describes a collaboration between our lab and Jose Argüello's lab at Worcester Polytechnic Institute, and we show that CusF can acquire Cu(I) from CopA. Our results from Chapters II and III show that CusF functions as a major copper chaperone in the periplasm of E. coli. Chapter IV details our work characterizing a novel protein from marine cyanobacteria, Synw_0921. Although Synw_0921 is believed to be involved in copper homeostasis, we show that it is an iron-sulfur cluster protein. Bioinformatic analysis suggests that Synw_0921 represents a new family of proteins that help marine cyanobacteria adapt to copper changes in their unique environment. Chapter V relates our work on CueR and GolS, two homologous sensor proteins with distinct metal-dependent transcriptional activation; we find that the activity cannot be explained by binding affinity differences. Chapter VI concludes with final thoughts on the intersection of biochemistry and molecular biology in the important process of understanding copper homeostasis.
Type:
text; Electronic Dissertation
Keywords:
Cyanobacteria; Esherichia coli; Iron-sulfur; Salmonella; Biochemistry; Copper homeostasis
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Biochemistry
Degree Grantor:
University of Arizona
Advisor:
McEvoy, Megan M.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleMolecular Mechanisms of Copper Homeostasis in Gram-negative Bacteriaen_US
dc.creatorGeorge Thompson, Alayna Michelleen_US
dc.contributor.authorGeorge Thompson, Alayna Michelleen_US
dc.date.issued2014-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.releaseRelease 2-May-2015en_US
dc.description.abstractCopper is a trace element utilized by organisms as a cofactor involved in redox chemistry, electron transport, photosynthesis, and oxidation reactions. In excess, copper is toxic; it can generate reactive oxygen species causing cellular damage, or poison other metalloproteins by replacing native metal cofactors. Gram-negative bacteria have developed homeostatic mechanisms to maintain the intracellular copper concentration in the face of changing environmental conditions. For Gram-negative enteric bacteria, like Esherichiacoli and Salmonella enterica serovar typhimurium, copper is encountered in industrial and institutional settings, where the metal is used as a broad-spectrum biocide. For environmental bacteria, such as the marine cyanobacterium Synechococcus sp. WH8102, copper stress occurs because human activity changes the concentration of copper in the ocean. This dissertation contains six chapters, relating four stories of our investigations into the molecular mechanisms of copper homeostasis in Gram-negative bacteria. Chapter I contains literature review and background on the implications of bacterial copper homeostasis. Chapter II reports our work investigating the expression of two E. coli proteins, CusF and CusB, upon copper stress; we show that CusF expresses at a ~10-fold molar excess over CusB. Chapter III describes a collaboration between our lab and Jose Argüello's lab at Worcester Polytechnic Institute, and we show that CusF can acquire Cu(I) from CopA. Our results from Chapters II and III show that CusF functions as a major copper chaperone in the periplasm of E. coli. Chapter IV details our work characterizing a novel protein from marine cyanobacteria, Synw_0921. Although Synw_0921 is believed to be involved in copper homeostasis, we show that it is an iron-sulfur cluster protein. Bioinformatic analysis suggests that Synw_0921 represents a new family of proteins that help marine cyanobacteria adapt to copper changes in their unique environment. Chapter V relates our work on CueR and GolS, two homologous sensor proteins with distinct metal-dependent transcriptional activation; we find that the activity cannot be explained by binding affinity differences. Chapter VI concludes with final thoughts on the intersection of biochemistry and molecular biology in the important process of understanding copper homeostasis.en_US
dc.typetexten
dc.typeElectronic Dissertationen
dc.subjectCyanobacteriaen_US
dc.subjectEsherichia colien_US
dc.subjectIron-sulfuren_US
dc.subjectSalmonellaen_US
dc.subjectBiochemistryen_US
dc.subjectCopper homeostasisen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineBiochemistryen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorMcEvoy, Megan M.en_US
dc.contributor.committeememberMcEvoy, Megan M.en_US
dc.contributor.committeememberBandarian, Vaheen_US
dc.contributor.committeememberCharest, Pascaleen_US
dc.contributor.committeememberCordes, Matthewen_US
dc.contributor.committeememberHorton, Nancyen_US
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