Turner, RaymondPushpker, Rajnigandha2017-07-042017-07-0420172017Pushpker, R. (2017). Evaluation of Genes for Escherichia coli Envelope Proteins for their Participation with the Small Multidrug Resistance Protein, EmrE, Mediated pH/Osmotic Tolerance (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25989http://hdl.handle.net/11023/3914The small multidrug resistance (SMR) protein, EmrE transports quaternary cationic compounds (QCC) across the cytoplasmic membrane in the Gram-negative bacterium Escherichia coli. EmrE over-expression results in the reduction of host pH and osmotic tolerance, likely through EmrE-mediated biological QCC based osmoprotectant efflux. It is not known how the substrates translocated by EmrE into the periplasmic space escape across the outer membrane (OM). The observation that an OM protein, OmpW, participates in EmrE-mediated substrate efflux provided the hypothesis that additional OM and periplasmic proteins participate in the process. By conducting alkaline pH based growth phenotype screens I identified 10 additional proteins that may contribute to the EmrE-mediated osmoprotectant efflux: GspD, HofQ, YccZ, AcrA, EmrA, EmrB, ProX, OsmF, DcrB and YggM. Further screening of these using a hyperosmotic stress ± betaine growth phenotype assay identified OmpW and two periplasmic proteins, DcrB and YggM, to have involvement in the EmrE-mediated export of betaine.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.MicrobiologyBiology--MolecularSmall Multidrug Resistance proteinEmrEGram-negative bacteriaOsmoprotectantsBetainemaster thesis10.11575/PRISM/25989