Related Experiment Video
Updated: Jul 22, 2026

In vitro Investigation of the MexAB Efflux Pump From Pseudomonas aeruginosa
Published on: February 18, 2014
Energy-coupled transport and signal transduction through the gram-negative outer membrane via
1Mikrobiologie II, Universität Tübingen, Germany.
Abstract:
Iron in the form of ferric siderophore complexes and vitamin B12 are transported through the outer membrane of Gram-negative bacteria by a mechanism which consumes energy. There is no known energy source in the outer membrane or in the adjacent periplasmic space so that energy is provided by the electrochemical potential across the cytoplasmic membrane. Energy flows from the cytoplasmic into the outer membrane via a complex consisting of the TonB, ExbB and ExbD proteins which are anchored in the cytoplasmic membrane. It is proposed that the TonB--ExbB--ExbD complex opens--via an energized conformation of the TonB protein--channels in the outer membrane, formed by proteins which serves as highly specific binding sites for the various ferric siderophores and vitamin B12. In addition, outer membrane receptors together with the TonB--ExbB--ExbD complex are directly involved in induction of the transcription of ferric citrate and pseudobactin transport genes of Escherichia coli and Pseudomonas putida, respectively.
Related Concept Videos
Protein Transport to the Thylakoids
G-Protein Gated Ion Channels
Sensory organs,...
Signal Transduction: Overview
Typically, signal transduction involves three...
Electron Transport Chain Components
Bacterial Translocation and Protein Secretion
Gram-negative Bacterial Protein Secretion Systems

