Peyton J Spreacker, Andrea K Wegrzynowicz, Colin J Porter, Will F Beeninga, Sydnye Demas, Emma N Powers, Katherine A Henzler-Wildman
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引用次数: 0
Abstract
Small multidrug resistance transporters efflux toxic compounds from bacteria and are a minimal system to understand multidrug transport. Most previous studies have focused on EmrE, the model SMR from Escherichia coli, finding that EmrE has a broader substrate profile than previously thought and that EmrE may perform multiple types of transport, resulting in substrate-dependent resistance or susceptibility. Here, we performed a broad screen to identify potential substrates of three other SMRs: PAsmr from Pseudomonas aeruginosa; FTsmr from Francisella tularensis; and SAsmr from Staphylococcus aureus. This screen tested metabolic differences in E. coli expressing each transporter versus an inactive mutant, for a clean comparison of sequence and substrate-specific differences in transporter function, and identified many substrates for each transporter. In general, resistance compounds were charged, and susceptibility substrates were uncharged, but hydrophobicity was not correlated with phenotype. Two resistance hits and two susceptibility hits were validated via growth assays and IC50 calculations. Susceptibility is proposed to occur via substrate-gated proton leak, and the addition of bicarbonate antagonizes the susceptibility phenotype, consistent with this hypothesis.
期刊介绍:
Molecular Microbiology, the leading primary journal in the microbial sciences, publishes molecular studies of Bacteria, Archaea, eukaryotic microorganisms, and their viruses.
Research papers should lead to a deeper understanding of the molecular principles underlying basic physiological processes or mechanisms. Appropriate topics include gene expression and regulation, pathogenicity and virulence, physiology and metabolism, synthesis of macromolecules (proteins, nucleic acids, lipids, polysaccharides, etc), cell biology and subcellular organization, membrane biogenesis and function, traffic and transport, cell-cell communication and signalling pathways, evolution and gene transfer. Articles focused on host responses (cellular or immunological) to pathogens or on microbial ecology should be directed to our sister journals Cellular Microbiology and Environmental Microbiology, respectively.