scholarly journals An allosteric transport mechanism for the AcrAB-TolC multidrug efflux pump

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Zhao Wang ◽  
Guizhen Fan ◽  
Corey F Hryc ◽  
James N Blaza ◽  
Irina I Serysheva ◽  
...  
Keyword(s):  
Transport Mechanism ◽  
Drug Transport ◽  
Efflux Pump ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Multidrug Efflux ◽  
Protein Assemblies ◽  
Multidrug Efflux Pump ◽  
Channel Opening ◽  
Activated State

Bacterial efflux pumps confer multidrug resistance by transporting diverse antibiotics from the cell. In Gram-negative bacteria, some of these pumps form multi-protein assemblies that span the cell envelope. Here, we report the near-atomic resolution cryoEM structures of the Escherichia coli AcrAB-TolC multidrug efflux pump in resting and drug transport states, revealing a quaternary structural switch that allosterically couples and synchronizes initial ligand binding with channel opening. Within the transport-activated state, the channel remains open even though the pump cycles through three distinct conformations. Collectively, our data provide a dynamic mechanism for the assembly and operation of the AcrAB-TolC pump.

scholarly journals Molecular Insights into an Antibiotic Enhancer Action of New Morpholine-Containing 5-Arylideneimidazolones in the Fight against MDR Bacteria

2021 ◽  
Vol 22 (4) ◽  
pp. 2062
Author(s):  
Aneta Kaczor ◽  
Karolina Witek ◽  
Sabina Podlewska ◽  
Veronique Sinou ◽  
Joanna Czekajewska ◽  
...  
Keyword(s):  
Molecular Modelling ◽  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Potential Mechanism ◽  
Multidrug Efflux ◽  
Aromatic Rings ◽  
Allosteric Site ◽  
Multidrug Efflux Pump ◽  
Dual Action

In the search for an effective strategy to overcome antimicrobial resistance, a series of new morpholine-containing 5-arylideneimidazolones differing within either the amine moiety or at position five of imidazolones was explored as potential antibiotic adjuvants against Gram-positive and Gram-negative bacteria. Compounds (7–23) were tested for oxacillin adjuvant properties in the Methicillin-susceptible S. aureus (MSSA) strain ATCC 25923 and Methicillin-resistant S. aureus MRSA 19449. Compounds 14–16 were tested additionally in combination with various antibiotics. Molecular modelling was performed to assess potential mechanism of action. Microdilution and real-time efflux (RTE) assays were carried out in strains of K. aerogenes to determine the potential of compounds 7–23 to block the multidrug efflux pump AcrAB-TolC. Drug-like properties were determined experimentally. Two compounds (10, 15) containing non-condensed aromatic rings, significantly reduced oxacillin MICs in MRSA 19449, while 15 additionally enhanced the effectiveness of ampicillin. Results of molecular modelling confirmed the interaction with the allosteric site of PBP2a as a probable MDR-reversing mechanism. In RTE, the compounds inhibited AcrAB-TolC even to 90% (19). The 4-phenylbenzylidene derivative (15) demonstrated significant MDR-reversal “dual action” for β-lactam antibiotics in MRSA and inhibited AcrAB-TolC in K. aerogenes. 15 displayed also satisfied solubility and safety towards CYP3A4 in vitro.

scholarly journals The assembled structure of a complete tripartite bacterial multidrug efflux pump

2009 ◽  
Vol 106 (17) ◽  
pp. 7173-7178 ◽  
Author(s):  
Martyn F. Symmons ◽  
Evert Bokma ◽  
Eva Koronakis ◽  
Colin Hughes ◽  
Vassilis Koronakis
Keyword(s):  
Efflux Pump ◽  
Cell Envelope ◽  
Adaptor Protein ◽  
Drug Binding ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Inner Membrane ◽  
Multidrug Efflux Pumps ◽  
Docking Approach

Bacteria likeEscherichia coliandPseudomonas aeruginosaexpel drugs via tripartite multidrug efflux pumps spanning both inner and outer membranes and the intervening periplasm. In these pumps a periplasmic adaptor protein connects a substrate-binding inner membrane transporter to an outer membrane-anchored TolC-type exit duct. High-resolution structures of all 3 components are available, but a pump model has been precluded by the incomplete adaptor structure, because of the apparent disorder of its N and C termini. We reveal that the adaptor termini assemble a β-roll structure forming the final domain adjacent to the inner membrane. The completed structure enabled in vivo cross-linking to map intermolecular contacts between the adaptor AcrA and the transporter AcrB, defining a periplasmic interface between several transporter subdomains and the contiguous β-roll, β-barrel, and lipoyl domains of the adaptor. With short and long cross-links expressed as distance restraints, the flexible linear topology of the adaptor allowed a multidomain docking approach to model the transporter–adaptor complex, revealing that the adaptor docks to a transporter region of comparative stability distinct from those key to the proposed rotatory pump mechanism, putative drug-binding pockets, and the binding site of inhibitory DARPins. Finally, we combined this docking with our previous resolution of the AcrA hairpin–TolC interaction to develop a model of the assembled tripartite complex, satisfying all of the experimentally-derived distance constraints. This AcrA3-AcrB3-TolC3model presents a 610,000-Da, 270-Å-long efflux pump crossing the entire bacterial cell envelope.

scholarly journals Genetic Variability of the AcrAB-TolC Multidrug Efflux Pump Underlies SkQ1 Resistance in Gram-Negative Bacteria

Acta Naturae ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 93-98 ◽  
Author(s):  
P. A. Nazarov ◽  
E. A. Kotova ◽  
V. P. Skulachev ◽  
Y. N. Antonenko
Keyword(s):  
Protein Sequence ◽  
Efflux Pump ◽  
Accessory Protein ◽  
Gram Negative Bacteria ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Chloramphenicol Resistance ◽  
Gram Negative ◽  
E Coli ◽  
Transporter Protein

SkQ1, a novel antibiotic targeting bacterial bioenergetics, is highly effective against both gram-positive and gram-negative bacteria. However, some gram-negative bacteria, such as Escherichia coli and Klebsiella pneumoniae, are highly resistant to it. In different gram-negative bacteria, this resistance is associated with the identity of their AcrB transporter protein sequence with the sequence of the AcrB protein from E. coli. SkQ1 is expelled from E. coli cells by the AcrAB-TolC multidrug efflux pump. In this study, we demonstrate that SkQ1 resistance in E. coli, in contrast to chloramphenicol resistance, does not depend on the presence of the multidrug efflux pump accessory protein AcrZ.

scholarly journals Modeling the Placement of the AcrAB-TolC Multidrug Efflux Pump in the Bacterial Cell Envelope

2020 ◽  
Vol 118 (3) ◽  
pp. 13a
Author(s):  
James C. Gumbart ◽  
Josie Ferreira ◽  
Sunny hwang ◽  
Anthony Hazel ◽  
Jerry M. Parks ◽  
...  
Keyword(s):  
Bacterial Cell ◽  
Efflux Pump ◽  
Cell Envelope ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Bacterial Cell Envelope

The pseudo-atomic structure of an RND-type tripartite multidrug efflux pump

2015 ◽  
Vol 396 (9-10) ◽  
pp. 1073-1082 ◽  
Author(s):  
Dijun Du ◽  
Jarrod Voss ◽  
Zhao Wang ◽  
Wah Chiu ◽  
Ben F. Luisi
Keyword(s):  
Antimicrobial Agents ◽  
Transmembrane Domain ◽  
Efflux Pump ◽  
Cell Envelope ◽  
Toxic Substances ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Transporter Family ◽  
Wide Range ◽  
Rnd Transporter

Abstract Microorganisms encode several classes of transmembrane molecular pumps that can expel a wide range of chemically distinct toxic substances. These machines contribute to the capacity of the organisms to withstand harsh environments, and they help to confer resistance against clinical antimicrobial agents. In Gram-negative bacteria, some of the pumps comprise tripartite assemblies that actively transport drugs and other harmful compounds across the cell envelope. We describe recent structural and functional data that have provided insights into the architecture and transport mechanism of the AcrA-AcrB-TolC pump of Escherichia coli. This multidrug efflux pump is powered by proton electrochemical gradients through the activity of AcrB, a member of the resistance/nodulation/cell division (RND) transporter family. Crystallographic data reveal how the small protein AcrZ binds to AcrB in a concave surface of the transmembrane domain, and we discuss how this interaction may affect the efflux activities of the transporter.

scholarly journals Threonine-978 in the Transmembrane Segment of the Multidrug Efflux Pump AcrB of Escherichia coli Is Crucial for Drug Transport as a Probable Component of the Proton Relay Network

2006 ◽  
Vol 188 (20) ◽  
pp. 7284-7289 ◽  
Author(s):  
Yumiko Takatsuka ◽  
Hiroshi Nikaido
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Bonding ◽  
Conformational Changes ◽  
Drug Transport ◽  
Efflux Pump ◽  
Relay Network ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Alanine Scanning Mutagenesis ◽  
Proton Relay

ABSTRACT Escherichia coli AcrB is a multidrug efflux transporter that recognizes multiple toxic chemicals and expels them from cells. It is a proton antiporter belonging to the resistance-nodulation-division (RND) superfamily. Asp407, Asp408, Lys940, and Arg971 in transmembrane (TM) helices of this transporter have been identified as essential amino acid residues that probably function as components of the proton relay system. In this study, we identified a novel residue in TM helix 11, Thr978, as an essential residue by alanine scanning mutagenesis. Its location close to Asp407 suggests that it is also a component of the proton translocation pathway, a prediction confirmed by the similar conformations adopted by T978A, D407A, D408A, and K940A mutant proteins (see the accompanying paper). Sequence alignment of 566 RND transporters showed that this threonine residue is conserved in about 96% of cases. Our results suggest the hypotheses that Thr978 functions through hydrogen bonding with Asp407 and that protonation of the latter alters the salt bridging and hydrogen bonding pattern in the proton relay network, thus initiating a series of conformational changes that ultimately result in drug extrusion.

scholarly journals Funnel-like Hexameric Assembly of the Periplasmic Adapter Protein in the Tripartite Multidrug Efflux Pump in Gram-negative Bacteria

2011 ◽  
Vol 286 (20) ◽  
pp. 17910-17920 ◽  
Author(s):  
Yongbin Xu ◽  
Minho Lee ◽  
Arne Moeller ◽  
Saemee Song ◽  
Bo-Young Yoon ◽  
...  
Keyword(s):  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Adapter Protein ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Gram Negative

scholarly journals Author response: An allosteric transport mechanism for the AcrAB-TolC multidrug efflux pump

2017 ◽  
Author(s):  
Zhao Wang ◽  
Guizhen Fan ◽  
Corey F Hryc ◽  
James N Blaza ◽  
Irina I Serysheva ◽  
...  
Keyword(s):  
Transport Mechanism ◽  
Efflux Pump ◽  
Author Response ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump

scholarly journals Structural and functional aspects of the multidrug efflux pump AcrB

2009 ◽  
Vol 390 (8) ◽  
Author(s):  
Thomas Eicher ◽  
Lorenz Brandstätter ◽  
Klaas M. Pos
Keyword(s):  
Conformational Changes ◽  
Drug Transport ◽  
Efflux Pump ◽  
Binding Pocket ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Substrate Binding Pocket ◽  
Functional Aspects ◽  
Transport Cycle ◽  
Multiple Antibiotics

Abstract The tripartite efflux system AcrA/AcrB/TolC is the main pump in Escherichia coli for the efflux of multiple antibiotics, dyes, bile salts and detergents. The inner membrane component AcrB is central to substrate recognition and energy transduction and acts as a proton/drug antiporter. Recent structural studies show that homotrimeric AcrB can adopt different monomer conformations representing consecutive states in an allosteric functional rotation transport cycle. The conformational changes create an alternate access drug transport tunnel including a hydrophobic substrate binding pocket in one of the cycle intermediates.

Sign in / Sign up

Export Citation Format

Share Document