Cellular fitness as a proxy to determine the physicochemical parameters of an antibiotic efflux pump

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dc.contributor.advisorShamoo, Yousifen_US
dc.contributor.advisorOlson, John Sen_US
dc.creatorPerez, Anisha Men_US
dc.date.accessioned2017-08-01T15:17:21Zen_US
dc.date.available2017-12-01T06:01:05Zen_US
dc.date.created2016-12en_US
dc.date.issued2016-12-02en_US
dc.date.submittedDecember 2016en_US
dc.date.updated2017-08-01T15:17:21Zen_US
dc.description.abstractDetermining the quantitative link between protein function and cellular fitness can be challenging as even the modestly sized genome of Escherichia coli is comprised of thousands of genes. Using an appropriate survey of fitness across a range of selective conditions, we can reduce the complexity of this system by tightly linking cellular fitness to the function of one protein essential for growth within that selective environment. Several model proteins have been studied in this fashion whereby in vitro protein parameters are used to predict cellular fitness as a function of selection strength. Underlying this approach, however, is the idea that the reverse relationship is also true: analysis of cellular fitness can be used to predict protein physicochemical properties. In this study I present a physiological model that uses cellular fitness as a proxy to predict the biochemical properties of the tetracycline efflux pump, TetB, and a family of strategically chosen single amino acid variants. TetB is a member of the Major Facilitator Superfamily (MFS) of transporters which have a conserved protein fold and for which we have a general understanding of how protein structure relates to function. We first performed growth rate analysis on our host strain without tet(B) at a wide range of drug concentrations to obtain global parameters that describe the baseline response of our cellular system. Growth analysis was also performed on strains expressing a chromosomal copy of tet(B) or variant allowing for a quantitative measurement of the fitness effects produced by TetB. Using both sets of fitness data and in vivo protein concentration, our model was able to predict physicochemical pump parameters relating to substrate binding affinity and pumping efficiency for TetB and variants which match the current knowledge of how MFS transporter structure influences function. Taken together, this study shows that cellular fitness in strong selective conditions can be used to characterize efflux pumps, a class of proteins which are classically challenging to characterize using classical in vitro biochemistry techniques. Additionally, this analysis opens up the possibility of characterizing protein libraries from high-throughput growth rate assays.en_US
dc.embargo.terms2017-12-01en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.citationPerez, Anisha M. "Cellular fitness as a proxy to determine the physicochemical parameters of an antibiotic efflux pump." (2016) Diss., Rice University. <a href="https://hdl.handle.net/1911/95961">https://hdl.handle.net/1911/95961</a>.en_US
dc.identifier.urihttps://hdl.handle.net/1911/95961en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectantibiotic resistanceen_US
dc.subjectefflux pumpen_US
dc.subjecttetracyclineen_US
dc.subjectmathematical modelen_US
dc.subjecttetBen_US
dc.subjecttet(B)en_US
dc.subjectfitnessen_US
dc.subjectcellular fitnessen_US
dc.subjectin vivoen_US
dc.titleCellular fitness as a proxy to determine the physicochemical parameters of an antibiotic efflux pumpen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentBiochemistry and Cell Biologyen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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