Discipline: Biological Sciences
Uyen Nguyen - University of Texas at Dallas
Co-Author(s): Karthik Hullahalli, University of Texas at Dallas, Richardson, TX; Kelli L. Palmer, University of Texas at Dallas, Richardson, TX.
Cells must go through the processes of replication, transcription, and translation in order to survive. During DNA replication, the double stranded DNA efficiently unwinds with the help of DNA gyrase. Levofloxacin (LVX), a fluoroquinolone antibiotic, binds tightly to DNA gyrase, preventing bacterial replication and resulting in cell death. Enterococcus faecalis is a Gram-positive bacterium that is normally found in gastrointestinal tracts. Infections by E. faecalis in hospital settings have been complicated by the rise in antibiotic resistance, leading to infections that now have limited treatment options. LVX remains a potential therapeutic strategy for many E. faecalis infections, and it is of interest to study how these organisms respond to LVX-induced stress. Examining these responses would provide insight into mechanisms that allow E. faecalis to overcome the lethal effects of a clinically relevant antibiotic, which may lead to improvement in LVX therapy. Previously, it was shown that over 600 genes are differentially regulated by LVX-induced stress through RNA-sequencing analysis. A subset of highly-induced genes involved in carbon metabolism that have no known role in the context of fluoroquinolone resistance were examined to determine if they provide tolerance to LVX. By utilizing a CRISPR-Cas9 genome editing system, genes in five major carbon metabolism pathways were deleted. Deletions were made in combinations to examine if each individual pathway was sufficient alone or in conjunction with others to provide LVX tolerance. Remarkably, the minimum inhibitory concentrations of LVX for these mutant strains remained the same relative to the wild-type, indicating that these carbon metabolism genes have no effect in LVX tolerance. This finding broadly reveals that specific changes in gene expression induced by antibiotic can have no role in direct antibiotic tolerance.
Funder Acknowledgement(s): NIH R01 Al116610 to K.L.P
Faculty Advisor: Kelli Palmer, email@example.com
Role: I conceptualized ideas and overall research goals, formalized analysis of data, conducted the research and investigation process by performing the experiments and data collection, designed experimental methodology, created and prepared the visualization, data presentation and writing the original draft.