ATP-binding cassette (ABC) transporters use the energy of ATP to move substrates across membranes against a concentration gradient. The role of ABC transporters is crucial in several essential cellular functions and mutations in ABC transporters in humans have been linked to several conditions, including cystic fibrosis, liver disease, and diabetes. Despite their central roles in homeostasis, the mechanism of ABC transporters remains poorly understood. Our research is focused on studying an ABC importer in E. coli, as a model system, to examine the mechanism of substrate specificity and transport. The bacterial methionine import system consists of a membrane-embedded transporter, MetNI, and a cognate binding protein, MetQ. Studies have been done of MetQ substrate specificity by purifying several variants of MetQ. Characterized by the binding affinities for methionine derivatives via the Isothermal Titration Calorimeter (ITC). Our data confirms that these mutations affect the binding affinities for methionine derivatives. For some mutations it removes the ability to bind to methionine itself. With these binding affinities in hand, further, experiments with the membrane-embedded transporter, MetNI, will be done in order to dissect the mechanism of ABC transporters.
Guardado, John H., "Substrate Specificity in ABC Transporters Using the E. coli Methionine Import System" (2023). Featured Student Work. 9.