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Related Experiment Video

Updated: May 19, 2026

Analyzing Telomeric Protein-DNA Interactions Using Single-Molecule Magnetic Tweezers

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Published on: August 30, 2024

Dissecting the function of a protruding loop in AcrB trimerization.

Jun Fang¹, Linliang Yu, Maria Wu

¹Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA.

Journal of Biomolecular Structure & Dynamics

|August 11, 2012

Summary

This summary is machine-generated.

The thumb loop in E. coli AcrB multidrug transporter is crucial for trimer stability and function. Mutations reveal flexibility, indicating specific interaction sites for stabilizing AcrB assembly.

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CRISPR-Mediated Reorganization of Chromatin Loop Structure

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Last Updated: May 19, 2026

Analyzing Telomeric Protein-DNA Interactions Using Single-Molecule Magnetic Tweezers

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The Development and Application of Biophysical Assays for Evaluating Ternary Complex Formation Induced by Proteolysis Targeting Chimeras (PROTACS)

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CRISPR-Mediated Reorganization of Chromatin Loop Structure

CRISPR-Mediated Reorganization of Chromatin Loop Structure

Published on: September 14, 2018

Area of Science:

Biochemistry
Molecular Biology
Structural Biology

Background:

AcrB from E. coli is a key multidrug transporter belonging to the resistance-nodulation-cell division (RND) family.
The AcrB homotrimer structure involves significant inter-subunit interactions mediated by a protruding loop and a binding tunnel.

Purpose of the Study:

To investigate the precise role of the protruding loop in AcrB trimerization and function.
To identify critical residues and interaction dynamics within the loop-tunnel interface.

Main Methods:

Alanine scanning mutagenesis of the loop region in AcrB.
Assessing the impact of mutations on AcrB protein activity and stability.
Construction and analysis of a chimeric protein using the MexB loop.

Main Results:

Not all conserved residues within the loop are essential for AcrB function; critical residues are not always conserved.
A chimeric AcrB protein with the MexB loop retained partial activity and existed as a mix of monomer and trimer.
Mutations causing reduced function clustered in specific areas, suggesting a potential inter-subunit recognition or stabilization site.

Conclusions:

The loop-tunnel interaction is vital for AcrB trimerization and efflux but demonstrates considerable flexibility and tolerance to mutations.
Specific regions within the loop may act as key sites for subunit recognition and stabilization during trimer formation.