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Structure of the MacAB-TolC ABC-type tripartite multidrug efflux pump.

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TLDR
In this article, an electron-cryo-microscopy structure of the ABC-type tripartite assembly of Escherichia coli was presented at near-atomic resolution.
Abstract
The MacA-MacB-TolC assembly of Escherichia coli is a transmembrane machine that spans the cell envelope and actively extrudes substrates, including macrolide antibiotics and polypeptide virulence factors. These transport processes are energized by the ATPase MacB, a member of the ATP-binding cassette (ABC) superfamily. We present an electron cryo-microscopy structure of the ABC-type tripartite assembly at near-atomic resolution. A hexamer of the periplasmic protein MacA bridges between a TolC trimer in the outer membrane and a MacB dimer in the inner membrane, generating a quaternary structure with a central channel for substrate translocation. A gating ring found in MacA is proposed to act as a one-way valve in substrate transport. The MacB structure features an atypical transmembrane domain with a closely packed dimer interface and a periplasmic opening that is the likely portal for substrate entry from the periplasm, with subsequent displacement through an allosteric transport mechanism.

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Journal ArticleDOI

Multidrug efflux pumps: structure, function and regulation

TL;DR: Recent advances that have increased understanding of the structures and molecular mechanisms of multidrug efflux pumps in bacteria are described, suggesting opportunities for countering their activities.
Journal ArticleDOI

Structural and functional diversity calls for a new classification of ABC transporters.

Christoph Thomas, +44 more
- 01 Dec 2020 - 
TL;DR: A new ABC transporter classification that currently comprises seven different types based on structural homology in the TMDs is proposed, suggesting that during evolution, the ancient motor domains were combined with different transmembrane mechanical systems to orchestrate a variety of cellular processes.
Journal ArticleDOI

Antibiotic resistance mediated by the MacB ABC transporter family : a structural and functional perspective

TL;DR: The MacB ABC transporter forms a tripartite efflux pump with the MacA adaptor protein and TolC outer membrane exit duct to expel antibiotics and export virulence factors from Gram-negative bacteria.
Journal ArticleDOI

Structure and mechanotransmission mechanism of the MacB ABC transporter superfamily

TL;DR: The structure of ATP-bound MacB is presented and precise molecular details of its mechanism are revealed, suggesting that the assembled tripartite pump acts as a molecular bellows to propel substrates through the TolC exit duct, driven by MacB mechanotransmission.
Journal ArticleDOI

Learning the ABCs one at a time: structure and mechanism of ABC transporters.

TL;DR: Recent progress on the structure determination of eukaryotic and bacterial ABC transporters as well as the novel mechanisms that have also been proposed, that fall out of the alternating access mechanism model are reviewed.
References
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Journal ArticleDOI

Comparison of simple potential functions for simulating liquid water

TL;DR: In this article, the authors compared the Bernal Fowler (BF), SPC, ST2, TIPS2, TIP3P, and TIP4P potential functions for liquid water in the NPT ensemble at 25°C and 1 atm.
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GROMACS: High performance molecular simulations through multi-level parallelism from laptops to supercomputers

TL;DR: GROMACS is one of the most widely used open-source and free software codes in chemistry, used primarily for dynamical simulations of biomolecules, and provides a rich set of calculation types.
Journal ArticleDOI

Comparison of multiple Amber force fields and development of improved protein backbone parameters.

TL;DR: An effort to improve the φ/ψ dihedral terms in the ff99 energy function achieves a better balance of secondary structure elements as judged by improved distribution of backbone dihedrals for glycine and alanine with respect to PDB survey data.
Journal ArticleDOI

RELION: implementation of a Bayesian approach to cryo-EM structure determination.

TL;DR: Developments that reduce the computational costs of the underlying maximum a posteriori (MAP) algorithm, as well as statistical considerations that yield new insights into the accuracy with which the relative orientations of individual particles may be determined are described.
Journal ArticleDOI

How Well Does a Restrained Electrostatic Potential (RESP) Model Perform in Calculating Conformational Energies of Organic and Biological Molecules

TL;DR: In this paper, the authors present conformational energies for a molecular mechanical model (Parm99) developed for organic and biological molecules using the restrained electrostatic potential (RESP) approach to derive the partial charges.
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