TY - JOUR TI - Structure of bacterial phospholipid transporter MlaFEDB with substrate bound AU - Coudray, Nicolas AU - Isom, Georgia L AU - MacRae, Mark R AU - Saiduddin, Mariyah N AU - Bhabha, Gira AU - Ekiert, Damian C A2 - Boudker, Olga A2 - Frost, Adam A2 - van den Berg, Bert A2 - Zimmer, Jochen VL - 9 PY - 2020 DA - 2020/11/25 SP - e62518 C1 - eLife 2020;9:e62518 DO - 10.7554/eLife.62518 UR - https://doi.org/10.7554/eLife.62518 AB - In double-membraned bacteria, phospholipid transport across the cell envelope is critical to maintain the outer membrane barrier, which plays a key role in virulence and antibiotic resistance. An MCE transport system called Mla has been implicated in phospholipid trafficking and outer membrane integrity, and includes an ABC transporter, MlaFEDB. The transmembrane subunit, MlaE, has minimal sequence similarity to other transporters, and the structure of the entire inner-membrane MlaFEDB complex remains unknown. Here, we report the cryo-EM structure of MlaFEDB at 3.05 Å resolution, revealing distant relationships to the LPS and MacAB transporters, as well as the eukaryotic ABCA/ABCG families. A continuous transport pathway extends from the MlaE substrate-binding site, through the channel of MlaD, and into the periplasm. Unexpectedly, two phospholipids are bound to MlaFEDB, suggesting that multiple lipid substrates may be transported each cycle. Our structure provides mechanistic insight into substrate recognition and transport by MlaFEDB. KW - cryo-EM KW - mla pathway KW - bacterial outer membrane KW - lipid transport JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -