TonB and the Gram‐negative dilemma

作者：Kathleen Postle · 发表于：Molecular Microbiology · 年份：1990 · DOI：10.1111/j.1365-2958.1990.tb00561.x · 被引用次数：219 · 研究领域：Bacterial Genetics and Biotechnology、Protein Structure and Dynamics、Antibiotic Resistance in Bacteria

TonB protein serves as an energy transducer to couple cytoplasmic membrane energy to high-affinity active transport of iron siderophores and vitamin B12 across the outer membranes of Gram-negative bacteria. The biochemical mechanism of the energy transduction remains to be determined, but important details are already known. TonB is targeted to and anchored in the cytoplasmic membrane by a single membrane-spanning domain and spans the periplasm to physically interact with outer-membrane receptors of the transport ligands. TonB-dependent energy transduction is modulated by ExbB protein, which stabilizes TonB, and possibly by several other proteins including ExbC, ExbD, and TolQ. TonB has a relatively short functional half-life that is accelerated when rates of active transport across the outer membrane are increased. A model that incorporates this information, as well as some tempered speculation, is presented.