The Conserved DedA/Tvp38 Membrane Protein Family Plays a Role in Antibiotic Resistance in Pseudomonas aeruginosa

Abstract

The highly conserved DedA/Tvp38 family of membrane proteins (DedA for short) is found in most bacterial species. Our laboratory has characterized DedA family members in the model organism Escherichia coli where deletion of the gene encoding one member of this family, YqjA, results in a sensitivity to alkaline pH. Additional deletion of a gene encoding a partially redundant protein YghB, with 62% amino acid sequence identity to YqjA, results in several phenotypes including a cell division defect and sensitivity to certain antibiotics and toxic compounds that are effluxed via known proton motive force (PMF) energized transporters. Based on these and other results we hypothesize that the DedA family is a new family of proton‐dependent membrane transporters.Pseudomonas aeruginosa is an opportunistic pathogen that is a major concern in hospitals as a nosocomial infection that easily takes advantage of weakened immune systems of patients. It is prevalent in burn wards, as well as among cancer patients, but it is most commonly associated with cystic fibrosis patients. Due to extensive drug resistance, this pathogen is notoriously difficult to treat. This is due in part to a multitude of PMF dependent antibiotic extrusion pumps from the multidrug and toxic compound extrusion (MATE) family, major facilitator superfamily (MFS), small multidrug resistance (SMR) family and the resistance‐nodulation‐division (RND) family. We therefore were interested in studying the effect of loss of DedA family members on drug resistance of P. aeruginosa.The genome of Pseudomonas aeruginosa PAO1 encodes five proteins belonging to the DedA family: PA1209, PA2752, PA4011, PA4029, and PA5244 (denoted PDedA1, PDedA2, PDedA3, PDedA4, and PDedA5, respectively). Transposon insertion mutants in each gene were acquired from the Manoil lab at the University of Washington. These studies were carried out by plating serial dilutions of strains on selective media and by directly measuring the minimal inhibitory concentrations (MIC) of antibiotics against the mutants. P. aeruginosa DedA family transposon mutants were each found to be 3–16 fold more sensitive to the clinically relevant fluoroquinolones antibiotics, ciprofloxacin and norfloxacin, as well as to acriflavine, chloramphenicol, and nalidixic acid as compared to the wild type.We also asked whether the P. aeruginosa DedA family genes could function in E. coli by measuring their ability to correct the phenotypes of E. coli DedA family mutants. We report that overexpression of PDedA4 and PDedA5 is able to correct the cell division defect and the antibiotic sensitivity of E. coli DyqjA, DyghB (denoted strain BC202). In addition, overexpression of these genes restores alkaline tolerance to the alkaline sensitive strain ΔyqjA.We conclude that DedA/Tvp38 family proteins are required for antibiotic resistance of Pseudomonas aeruginosa and at least two (PDedA4 and PDedA5) share common functions with and can substitute for Escherichia coli YqjA and YghB.