Vitamin B12 transport in Escherichia coli: energy coupling between membranes

作者：Robert J. Kadner · 发表于：Molecular Microbiology · 年份：1990 · DOI：10.1111/j.1365-2958.1990.tb00562.x · 被引用次数：223 · 研究领域：Bacterial Genetics and Biotechnology、Bacteriophages and microbial interactions、Porphyrin Metabolism and Disorders

Cells of Escherichia coli possess high-affinity active transport systems of vitamin B12 and iron-siderophore complexes. Specific outer-membrane proteins carry out the energy-dependent transport across the outer membrane, in conjunction with the TonB coupling protein. Mutagenesis experiments have identified a conserved region near the amino-terminus of the outer-membrane transporters that is necessary for energy-coupled transport. The ability of extragenic suppressor mutations in tonB to correct the transport defect indicates that TonB couples the proton-motive force to the outer-membrane proteins by direct contact.