The increasing prevalence of antibiotic-resistant bacteria is a growing public health threat that must be addressed. One way that bacteria become resistant to antibiotics is through the use of multidrug transporters, membrane proteins that pump foreign molecules out of the cell. Thus, understanding how these proteins work could lead to the design of new drugs that can prevent this mechanism of antibiotic resistance. To this end, Basic Sciences investigator Hassane Mchaourab in collaboration with Cédric Govaerts (Université Libre de Bruxelles) has investigated the structural basis for the action of the Lactococcus lactis multidrug transporter LmrP, which exchanges a wide range of positively charged molecules in exchange for a proton. Their work builds on prior studies of the movement of LmrP upon substrate or proton binding. This work provided important insight into the function of the protein, but the investigators were concerned that their use of detergent to solubilize LmrP placed the protein in a nonphysiological environment. In their new work, the researchers studied the motions of LmrP in membrane nanodiscs to more closely mimic the protein’s natural state. Their results mostly agreed with the prior findings; however in the nanodisc, the protein’s motions occurred in a more physiological pH range and the key amino acids that coordinated the motions were more tightly coupled than in the detergent environment. This was likely due to a tight interaction between the protein and lipids in the membrane. The results provide key insights into the function of a prototypical multidrug transporter and demonstrate the importance of carrying out experiments such as these under conditions that resemble the natural environment as closely as possible. The work is published in the journal Nature Structural and Molecular Biology [C. Martens, et al. (2016), Nat. Struct. Mol. Biol., published online July 11, doi: 10.1038/nsmb.3262].