The Tol–Pal system of Escherichia coli plays an unexpected role in the import of the oxyanions chromate and phosphate

Direct interaction between fd phage pilot protein pIII and the TolQ–TolR proton-dependent motor provides new insights into the import of filamentous phages

“…The flux of protons is converted into mechanical movements transduced to the TolA protein, which interacts with the OM lipoprotein Pal and with the periplasmic protein TolB ( 34 , 35 , 36 ). In E. coli , mutants of the Tol–Pal system display numerous defects collectively called tol phenotypes, such as a chaining morphology in low osmotic medium, hypersensitivity to detergents, resistance to Tol-dependent toxins called colicins ( 37 ), and increased resistance to chromate ( 38 ). Thorough analysis of these pleiotropic phenotypes over the past 50 years demonstrated that the Tol–Pal complex is crucial in envelope integrity maintenance, OM lipid homeostasis, and in the late stage of cell division ( 39 , 40 , 41 , 42 , 43 ).…”