Date: 23.06.2023, Time: 15:30h

Location: Kleiner Physikhörsaal N020, Fakultät für Physik
The talk will also be streamed online.

The maltose transporter is a bacterial nutrient import system and one of the most well studied ATP Binding Cassette (ABC) transporters. The goal of the seminar is to outline the mechanisms that ensure very tight coupling between ATP hydrolysis and transmembrane maltose transport. The maltose transporter consists of an integral membrane complex, MalFGK2, and a peripheral substrate binding subunit, maltose binding protein (MBP). Tight energetic coupling is achieved through three mechanisms that all depend on interactions between MBP and MalFGK2; the transport of maltose is only indirectly coupled to ATPase activity. The first step is the binding of maltose-loaded MBP to MalFGK2 that facilitates a conformational change in the system and initiates the ATPase cycle; the second step is a recognition by the system that substrate has been transferred from MBP to MalFGK2; and the last step is the prevention of substrate escape or backsliding as the system returns to its initial state and deposits maltose into the cytoplasm. These mechanisms, and the accompanying kinetic and thermodynamic considerations, explain the very efficient chemical-mechanical coupling in the maltose transporter and a provide a framework for understanding energetic coupling in other energy transducing systems.