Crystal Structure of Bacterial Multi-Drug Efflux Transporter AcrB

2003 Nihon Kessho Gakkaishi  
AcrB is a major multidrug exporter in Escherichia coli. It cooperates with a membrane fusion protein, AcrA, and an outer membrane channel, TolC. We have determined the crystal structure of AcrB at 3.5 Å resolution. Three AcrB protomers are organized as a homotrimer in the shape of a jellyfish. Each protomer is composed of a transmembrane region 50 Å thick and a 70 Å protruding headpiece. The top of the headpiece opens like a funnel, where TolC might directly dock into AcrB. A pore formed by
more » ... e a-helices connects the funnel with a central cavity located at the bottom of the headpiece. The cavity has three vestibules at the side of the headpiece which lead into the periplasm. In the transmembrane region, each protomer has twelve transmembrane a-helices. The structure implies that substrates translocated from the cell interior through the transmembrane region and from the periplasm through the vestibules are collected in the central cavity and then actively transported through the pore into the TolC tunnel. electron density map. This figure was prepared with program O (ref. 41). Thirty-eight selenium atoms are depicted as red balls. articles NATURE | VOL 419 | 10 OCTOBER 2002 | 587
doi:10.5940/jcrsj.45.256 fatcat:pdvpgme26vcedjnfvi7j4qeffy