Cryo-EM structures of Acinetobacter baumannii glycerophospholipid transporter
Yuanyuan Zhang, Qiongxuan Fan, Ximin Chi, Qiang Zhou, Yanyan Li
Abstract
Acinetobacter baumannii is a prevalent nosocomial pathogen that causes serious threat in health care institutions 1 . A. baumannii has demonstrated resistance to a wide array of antibiotics, including the last-resort colistin or polymyxin B 2 , 3 , 4 . The MlaFEDB-mediated glycerophospholipid (PL) transport was reported to play an important role in maintaining the integrity of the lipid membrane 2 , 3 . The MlaFEDB complex is an ATP-binding cassette transporter to actively translocate the phospholipids between the inner membrane and the periplasmic protein MlaC 4 , 5 . Despite the progress that has been made in understanding the function of the MlaFEDB complex by genetic and biochemical strategies in A. baumannii , questions still remain open surrounding the directionality in glycerophospholipids transport via MlaFEDB in both retrograde and anterograde transport 6 , 7 . The low-resolution structure of the MlaFEDB complex from A. baumannii at 8.7 Å has provided initial structural insights into this complex 8 . However, the molecular details of the transport complex assembly, the interactions with glycerophospholipids, and the transport mechanisms of the MlaFEDB in A. baumannii remain enigmatic.