Examining the Bacterial Methionine Transporter Utilizing Soluble Lipid Bilayer Systems

ATP-binding cassette (ABC) transporters are ubiquitous across all kingdoms of life. These highly specific pumps translocate substrates across cell membranes through the energy from ATP binding and hydrolysis. A detailed understanding of ABC transporter mechanism could aid in the treatment of a variety of human disorders in which ABC transporters are defective such as cystic fibrosis. While the structural determinations of ABC transporters have provided critical insights, a detailed molecular understanding of how these proteins work has been precluded by difficulties in the functional study of transporters such as unstable “substitute” mimetic environments. To address this issue, we have turned to a system called nanodiscs, which is a discoidal lipid bilayer encircled by a protein helical belt. Unlike liposomes, nanodiscs have been shown to be a viable system for fluorescent spectroscopic analysis. In preparation for, and as subject to, these kind of analyses, this system has been experimentally proven to be durable in a wide range of experimental conditions, including pH, temperature, and salt concentration.