C V Franklund

Chapter 28 Communication between membranes in tonB-dependent transport across the bacterial outer membrane

Publisher Summary Gram-negative bacteria comprise the majority of the bacterial world. The defining structural feature of Gram-negative bacteria, and a major factor in their evolutionary success, is the presence of an outer membrane surrounding the cytoplasmic membrane and peptidoglycan layer. Compared to other biological membranes, the outer membrane characteristically has a very unusual composition, lipid asymmetry, protein content, and function. Outer membranes usually exhibit surprisingly low permeability by hydrophobic compounds and high permeability by polar compounds, owing to their unusual lipid content and the presence of porin channels, respectively. They protect the cell from toxic enzymes and nonpolar compounds, including detergents and many antibiotics, and thus have profound influence on the cells physiological, medical, and ecological capabilities. This chapter reviews the structure, mechanism, and interactions of the components of a family of active nutrient transport systems that are located in the outer membrane.