Elizabeth M Fozo

Elizabeth M Fozo
University of Tennessee | UTK · Department of Microbiology

Ph.D.

About

41
Publications
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1,546
Citations

Publications

Publications (41)
Article
Type I toxin-antitoxin systems consist of a small protein (under 60 amino acids) whose overproduction can result in cell growth stasis or death, and a small RNA that represses translation of the toxin mRNA. Despite their potential toxicity, type I toxin proteins are increasingly linked to improved survival of bacteria in stressful environments and...
Article
Full-text available
Daptomycin is a cyclic lipopeptide antibiotic used in the clinic for treatment of severe enterococcal infections. Recent reports indicate that daptomycin targets active cellular processes, specifically, peptidoglycan biosynthesis. Within, we examined the efficacy of daptomycin against Enterococcus faecalis under a range of environmental growth cond...
Article
Full-text available
The bacterial lipid membrane, consisting both of fatty acid (acyl) tails and polar head groups, responds to changing conditions through alteration of either the acyl tails and/or head groups. This plasticity is critical for cell survival as it allows maintenance of both the protective nature of the membrane as well as functioning membrane protein c...
Article
Full-text available
With an increasing prevalence of antibiotic resistance in the clinic, we strive to understand more about microbial defensive mechanisms. A nongenetic tolerance to the antibiotic daptomycin was discovered in Enterococcus faecalis that results in the increased survival of bacterial populations after treatment with the drug. This tolerance mechanism l...
Article
Bacterial membranes are complex mixtures with dispersity that is dynamic over scales of both space and time. To capture adsorption onto and transport within these mixtures, we conduct simultaneous second harmonic generation (SHG) and two-photon fluorescence measurements on two different gram-positive bacterial species as the cells uptake membrane-s...
Preprint
Bacterial membranes are complex mixtures with dispersity that is dynamic over scales of both space and time. In order to capture adsorption onto and transport within these mixtures, we conduct simultaneous second harmonic generation (SHG) and two photon fluorescence measurements on two different gram-positive bacterial species as the cells uptake m...
Article
Full-text available
Introduction Lipidomics can reveal global alterations in a broad class of molecules whose functions are innately linked to physiology. Monitoring changes in the phospholipid composition of biological membranes in response to stressors can aid the development of targeted therapies. However, exact quantitation of cardiolipins is not a straightforward...
Article
Full-text available
Microcystins are secondary metabolites produced by several freshwater, bloom-forming cyanobacterial species. Microcystin-producing cyanobacteria co-occur with a complex community of heterotrophic bacteria. Though conflicting, studies suggest that microcystins affect the physiology of heterotrophic bacteria by inducing oxidative stress and increasin...
Data
Example growth curve of E. coli. Growth curves of E. coli in M9 minimal medium with addition of 4 g L-1 glucose and 1 mg L-1 thiamine HCl. These curves were generated in preliminary experiments and represent conditions identical to those of the master cultures described in Methods. Treatments were imposed on cultures approximately 8 hr after inocul...
Data
Relative concentration of amino acids responsive to oxidative stress. Error bars represent 1 S.E. (TIF)
Data
Relative concentration of glycolysis and TCA cycle metabolites responsive to oxidative stress. Error bars represent 1 S.E. (TIF)
Data
Summary of RNA sequencing libraries. (DOCX)
Data
Excel spreadsheet containing metabolite data normalized to optical density of cultures. (XLSX)
Data
Excel spreadsheet containing lipid data normalized to optical density of cultures. (XLSX)
Data
O.D.600 of treatment and control cultures. O.D.600 measurements of cultures at the start (time = 0) and end (time = 60 min) of treatments. Symbols represent actual data points of biological replicates. The horizontal bars represent the mean. (TIF)
Data
Fold change in Bae, Psp, and Rcs regulon gene expression for 10-mg/L MCLR treatment. Each point represents the log2 fold change relative to control at a given time point. The horizontal line at 0 represents equal expression in treatment and control. Gene abbreviations: Bae regulon: mdtB (multidrug efflux pump RND permease subunit). Psp regulon: psp...
Data
Relative concentration of glutathione and glutathione disulfide. Error bars represent 1 S.E. (TIF)
Conference Paper
Metabolomics aims to answer biological questions using analytical chemistry tools by measuring alterations in intracellular metabolite levels. In conjunction with their rates of change, a temporal snapshot of how these small molecules fluctuate in major cellular pathways can also be assembled. Using these metabolomic approaches, it is possible to e...
Article
Many bacterial type I toxin mRNAs possess a long 5' untranslated region (UTR) that serves as the target site of the corresponding antitoxin sRNA. This is the case for the zorO-orzO type I system where the OrzO antitoxin base pairs to the 174-nucleotide zorO 5' UTR. Here, we demonstrate that the full-length 5' UTR of the zorO type I toxin hinders it...
Chapter
In order to survive environmental stressors, including those induced by growth in the human host, bacterial pathogens will adjust their membrane physiology accordingly. These physiological changes also include the use of host-derived lipids to alter their own membranes and feed central metabolic pathways. Within the host, the pathogen is exposed to...
Article
Full-text available
Importance statement: Enterococcus faecalis is responsible for a significant number of nosocomial infections. Worse, many of the antibiotics used to treat E. faecalis infection are no longer effective as this organism has developed resistance to them. The drug daptomycin has been successfully used to treat some of these resistant strains; however,...
Article
Full-text available
Enterococcus faecalis is a commensal bacterium of the mammalian intestine that can persist in soil and aquatic systems and can be a nosocomial pathogen to humans. It employs multiple stress adaptation strategies in order to survive such a wide range of environments. Within this study, we sought to elucidate whether membrane fatty acid composition c...
Article
Full-text available
Bacterial toxin-antitoxin loci consist of two genes: one encodes a potentially toxic protein, and the second, an antitoxin to repress its function or expression. The antitoxin can either be an RNA or a protein. For type I and type III loci, the antitoxins are RNAs; however, they have very different modes of action. Type I antitoxins repress toxin p...
Article
The antimicrobial behavior of Cu-bearing Zr-based bulk metallic glasses (BMGs) was investigated for the first time against the Gram positive bacterium Staphylococcus aureus to evaluate their potential applications in healthcare settings. Despite their lack of bacteria-killing effect under a relatively severe experimental setting of dynamic immersio...
Article
Full-text available
Type I toxin–antitoxin loci consist of two genes: a small, hydrophobic, potentially toxic protein, and a small RNA (sRNA) antitoxin. The sRNA represses toxin gene expression by base pairing to the toxin mRNA. A previous bioinformatics search predicted a duplicated type I locus within Escherichia coli O157:H7 (EHEC), which we have named the gene pai...
Chapter
Although plasmid encoded type I TA loci have been known for many years, recent discoveries have identified novel, chromosomally encoded type I loci. Many novel type I families have now been identified but their exact biological roles are not known. Here, I describe their discovery, their distribution, and the possible functions for these unusual ge...
Article
Type I toxin-antitoxin loci consist of two genes: one encodes a small, toxic protein and the second encodes a small RNA antitoxin that represses toxin gene expression. These pairs were first described on plasmids where they regulate plasmid maintenance. However, recent discoveries have found novel type I loci, with no homology to plasmid sequences,...
Article
The adjacent gadX and gadW genes encode transcription regulators that are part of a complex regulatory circuit controlling the Escherichia coli response to acid stress. We previously showed that the small RNA GadY positively regulates gadX mRNA levels. The gadY gene is located directly downstream of the gadX coding sequence on the opposite strand o...
Article
Full-text available
Small, hydrophobic proteins whose synthesis is repressed by small RNAs (sRNAs), denoted type I toxin–antitoxin modules, were first discovered on plasmids where they regulate plasmid stability, but were subsequently found on a few bacterial chromosomes. We used exhaustive PSI-BLAST and TBLASTN searches across 774 bacterial genomes to identify homolo...
Article
Summary The sequences encoding the QUAD1 RNAs were ini- tially identified as four repeats in Escherichia coli. These repeats, herein renamed SIB, are conserved in closely related bacteria, although the number of repeats varies. All five Sib RNAs in E. coli MG1655 are expressed, and no phenotype was observed for a five-sib deletion strain. However,...
Article
Full-text available
There has been a great expansion in the number of small regulatory RNAs identified in bacteria. Some of these small RNAs repress the synthesis of potentially toxic proteins. Generally the toxin proteins are hydrophobic and less than 60 amino acids in length, and the corresponding antitoxin small RNA genes are antisense to the toxin genes or share l...
Article
Full-text available
An insertionally inactivated fabM strain of Streptococcus mutans does not produce unsaturated membrane fatty acids and is acid sensitive (E. M. Fozo and R. G. Quivey, Jr., J. Bacteriol. 186:4152-4158, 2004). In this study, the strain was shown to be poorly transmissible from host to host. Animals directly infected with the fabM strain exhibited few...
Article
Four oral bacterial strains, of which two are considered aciduric and two are considered acid-sensitive, were grown under glucose-limiting conditions in chemostats to determine whether their membrane fatty acid profiles were altered in response to environmental acidification. Streptococcus gordonii DL1, as well as the aciduric strains S. salivarius...
Article
Full-text available
Previously, it has been demonstrated that the membrane fatty acid composition of Streptococcus mutans is affected by growth pH (E. M. Fozo and R. G. Quivey, Jr., Appl. Environ. Microbiol. 70:929-936, 2004; R. G. Quivey, Jr., R. Faustoferri, K. Monahan, and R. Marquis, FEMS Microbiol. Lett. 189:89-92, 2000). Specifically, the proportion of monounsat...
Article
Full-text available
Acid adaptation of Streptococcus mutans UA159 involves several different mechanisms, including the ability to alter its proportion of long-chain, monounsaturated membrane fatty acids (R. G. Quivey, Jr., R. Faustoferri, K. Monahan, and R. Marquis, FEMS Microbiol. Lett. 189:89-92, 2000). In the present study, we examined the mechanism and timing of c...
Article
Full-text available
The gene encoding a nitric oxide reductase has been identified inNeisseria gonorrhoeae. The norB gene product shares significant identity with the nitric oxide reductases inRalstonia eutropha and Synechocystis sp. and, like those organisms, the gonococcus lacks a norC homolog. The gonococcal norB gene was found to be required for anaerobic growth,...

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