scholarly journals Functional phenotyping of small multidrug resistance proteins from Staphylococcus aureus and Francisella tularensis reveals functional homology to EmrE

2021 ◽  
Author(s):  
Peyton J Spreacker ◽  
Will F Beeninga ◽  
Brooke L Young ◽  
Colin J Porter ◽  
Katherine A Henzler-Wildman
Keyword(s):  
Staphylococcus Aureus ◽  
Multidrug Resistance ◽  
Substrate Specificity ◽  
Francisella Tularensis ◽  
Bacterial Species ◽  
Toxic Metabolite ◽  
Bacterial Cells ◽  
Multidrug Resistance Proteins ◽  
Antibiotic Development ◽  
Small Multidrug Resistance

Small multidrug resistance (SMR) transporters efflux toxic substrates from bacterial cells. These transporters were recently divided into two subfamilies: the GdX-like and EmrE-like SMRs. The EmrE-like subfamily of SMRs is predicted to contain transporters that are highly promiscuous in both substrate specificity and mechanism based on extensive characterization of the founding member of this subfamily, EmrE. However, there is only limited functional analysis of other members of this family from pathogenic strains such as Staphylococcus aureus and Francisella tularensis. Here, we use a small compound screen to explore the substrate specificity and diversity of EmrE-subfamily SMRs from these two bacterial species and confirm that they are functionally more like EmrE than the GdX-like subfamily of toxic-metabolite transporters. The results of these experiments lay the foundation for understanding the complex substrate specificity profiles of SMR family transporters and assess the potential for targeting these transporters for future antibiotic development, either broadly or in a species-specific manner.

scholarly journals Drug Efflux by a Small Multidrug Resistance Protein Is Inhibited by a Transmembrane Peptide

2012 ◽  
Vol 56 (7) ◽  
pp. 3911-3916 ◽  
Author(s):  
Bradley E. Poulsen ◽  
Charles M. Deber
Keyword(s):  
Multidrug Resistance ◽  
Rate Constant ◽  
Halobacterium Salinarum ◽  
Resistant Bacteria ◽  
Bacterial Cells ◽  
Multidrug Resistance Proteins ◽  
Content Type ◽  
Hydrophobic Peptides ◽  
Small Multidrug Resistance ◽  
Efflux Rate Constant

ABSTRACTDrug-resistant bacteria use several families of membrane-embedded transporters to remove antibiotics from the cell. One such family is the small multidrug resistance proteins (SMRs) that, because of their relatively small size (ca. 110 residues with four transmembrane [TM] helices), must form (at least) dimers to efflux drugs. Here, we use a Lys-tagged synthetic peptide with exactly the same sequence as TM4 of the full-length SMR Hsmr fromHalobacterium salinarum[TM4 sequence: AcA(Sar)3-VAGVVGLALIVAGVVVLNVAS-KKK (Sar =N-methylglycine)] to compete with and disrupt the native TM4-TM4 interactions believed to constitute the locus of Hsmr dimerization. Using a cellular efflux assay of the fluorescent SMR substrate ethidium bromide, we determined that bacterial cells containing Hsmr are able to remove cellular ethidium via first-order exponential decay with a rate constant (k) of 10.1 × 10−3± 0.7 × 10−3s−1. Upon treatment of the cells with the TM4 peptide, we observed a saturable ∼60% decrease in the efflux rate constant to 3.7 × 10−3± 0.2 × 10−3s−1. In corresponding experiments with control peptides, including scrambled sequences and a sequence withd-chirality, a decrease in ethidium efflux either was not observed or was marginal, likely from nonspecific effects. The designed peptides did not evoke bacterial lysis, indicating that they act via the α-helicity and membrane insertion propensities of the native TM4 helix. Our overall results suggest that this approach could conceivably be used to design hydrophobic peptides for disruption of key TM-TM interactions of membrane proteins and represent a valuable route to the discovery of new therapeutics.

scholarly journals Multidrug Resistance Efflux Pumps in Acinetobacter spp.: An Update

2021 ◽  
Author(s):  
Vanessa Kornelsen ◽  
Ayush Kumar
Keyword(s):  
Multidrug Resistance ◽  
Antimicrobial Resistance ◽  
Bacterial Species ◽  
Clinical Importance ◽  
Efflux Pumps ◽  
Major Facilitator Superfamily ◽  
Small Multidrug Resistance ◽  
Resistance Nodulation Division ◽  
Rnd Efflux Pumps ◽  
Major Facilitator

Acinetobacter spp. have become of increased clinical importance as studies have shown the antimicrobial resistant potential of these species. Efflux pumps can lead to reduced susceptibility to a variety of antibiotics and are present in large number across Acinetobacter spp. There are six families of efflux pumps that have been shown to be of clinical relevance: the Major Facilitator Superfamily (MFS), Small Multidrug Resistance (SMR) family, ATP-binding cassette (ABC) family, Multidrug and Toxic Compound Extrusion (MATE) family, Proteobacterial Antimicrobial Compound Efflux (PACE) family and Resistance-Nodulation-Division (RND) family. A lot of work has been done on understanding and characterizing the roles that these efflux pumps play in relation to antimicrobial resistance and the physiology of these bacteria. RND efflux pumps, with their expansive substrate profiles, are a major component of Acinetobacter spp. antimicrobial resistance. New discoveries over the last decade have shed a lot of light on to the complex regulation of these efflux pumps leading to greater understanding and potential of slowing the reduced susceptibility seen by these bacterial species.

scholarly journals Identification of Domains Participating in the Substrate Specificity and Subcellular Localization of the Multidrug Resistance Proteins MRP1 and MRP2

2003 ◽  
Vol 278 (25) ◽  
pp. 22908-22917 ◽  
Author(s):  
Toshikazu Konno ◽  
Takuya Ebihara ◽  
Keiji Hisaeda ◽  
Takeshi Uchiumi ◽  
Takanori Nakamura ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Substrate Specificity ◽  
Subcellular Localization ◽  
Multidrug Resistance Proteins ◽  
Resistance Proteins
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