Related Experiment Video

Updated: Aug 7, 2026

Expression, Detergent Solubilization, and Purification of a Membrane Transporter, the MexB Multidrug Resistance Protein
10:43

Expression, Detergent Solubilization, and Purification of a Membrane Transporter, the MexB Multidrug Resistance Protein

Published on: December 3, 2010

No single irreplaceable acidic residues in the Escherichia coli secondary multidrug transporter MdfA

Nadejda Sigal1, Shahar Molshanski-Mor, Eitan Bibi

  • 1Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.

Journal of Bacteriology
|July 21, 2006
PubMed

Insights

The major facilitator superfamily (MFS) includes proton-motive-force-driven transporters. Our study reveals that no single acidic residue is essential for the function of the Escherichia coli multidrug transporter MdfA.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Structural Biology

Background:

  • The major facilitator superfamily (MFS) is the largest family of secondary active transporters.
  • MFS transporters utilize proton-motive force for substrate translocation.
  • Essential acidic residues are known to be critical for energy coupling in several MFS transporters.

Purpose of the Study:

  • To investigate the role of acidic residues in the energy-coupling mechanism of the Escherichia coli multidrug transporter MdfA.
  • To determine if any single acidic residue is irreplaceable for MdfA function.

Main Methods:

  • Site-directed mutagenesis of conserved acidic residues in MdfA.
  • In vitro transport assays to measure substrate uptake.
  • Computational modeling to analyze structural implications.

Main Results:

  • Mutational analysis demonstrated that no single acidic residue is essential for MdfA-mediated transport.
  • Multiple acidic residues can be altered or removed without complete loss of function.
  • This suggests a redundant or distributed role for acidic residues in MdfA's energy transduction.

Conclusions:

  • The energy-coupling mechanism of MdfA does not rely on a single indispensable acidic residue.
  • MdfA exhibits functional redundancy in its acidic residues, challenging previous models for MFS transporters.
  • These findings provide new insights into the transport mechanism of MFS proteins.

More Related Videos

Characterizing Multidrug Efflux Systems in Acinetobacter baumannii Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System05:06

Characterizing Multidrug Efflux Systems in Acinetobacter baumannii Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System

Published on: January 5, 2024

In vitro Investigation of the MexAB Efflux Pump From Pseudomonas aeruginosa13:40

In vitro Investigation of the MexAB Efflux Pump From Pseudomonas aeruginosa

Published on: February 17, 2014

Related Concept Videos

ABC Transporters: Exporter01:31

ABC Transporters: Exporter

ATP-binding cassette or ABC transporter is the largest superfamily of integral membrane proteins. The transporters have transmembrane-binding domains (TMDs) and nucleotide-binding domains (NBDs). The TMDs are specific to their substrates, whereas the NBDs are similar to engines that complete ATP hydrolysis to complete the substrate transport. They can be full transporters consisting of two TMDs and NBDs, half transporters with one TMD and NBD, while some encoded with a single TMD or NBD are...
Carrier-Mediated Transport01:06

Carrier-Mediated Transport

Carrier-mediated transport is a pivotal process in drug absorption, particularly for lipid-insoluble drugs, and encompasses facilitated diffusion and active transport. Facilitated diffusion allows drugs to move along their concentration gradient without energy expenditure, while active transport utilizes ATP to drive drug movement against this gradient.
Active transport involves two types of membrane-spanning transporters: uptake and efflux. Uptake transporters are expressed in the small...
ABC Transporters: Importer01:27

ABC Transporters: Importer

ATP-binding cassette or ABC transporters are a class of ATP-driven pumps that hydrolyze ATP to move solutes across the membrane. They can be grouped into importers and exporters. While exporters are present in all domains of life, importers exist only in bacteria and some plants.
In bacteria, based on the number of transmembrane helices and the chemical nature of their substrates, the ABC importers can be divided into three types:
Development of Antibiotic Resistance01:30

Development of Antibiotic Resistance

Antibiotic resistance is a major public health concern that arises when bacteria evolve mechanisms to withstand the effects of antibiotic treatments. This resistance can be intrinsic, acquired through genetic mutations, or transferred between bacteria via horizontal gene transfer. The development of antibiotic resistance poses significant challenges in treating bacterial infections and necessitates ongoing research to develop new therapeutic strategies.Intrinsic resistance occurs when bacterial...
The Significance of Membrane Transport01:44

The Significance of Membrane Transport

The transport of solutes across the cell membrane is essential for metabolic processes, like maintaining cell size and volume, generating the action potential, exchanging nutrients and gases, etc. Membrane transport can be either passive or active. It can be simple diffusion, facilitated, or mediated transport aided by transport proteins such as transporters and channels.
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
Mechanism of Antibiotic Resistance in MRSA01:25

Mechanism of Antibiotic Resistance in MRSA

Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and acquisition...