Energy‐coupled transport through the outer membrane of Escherichia coli small deletions in the gating loop convert the FhuA transport protein into a diffusion channel

FEBS Letters

Braun, Volkmar¹  Benz, Roland²  Killmann, Helmut¹ 

[1] Mikrobiologie/Membranphysiologie, Universität Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany;Biotechnologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany

关键词: Gated FhuA channel;    E. coli;    Outer membrane;   

DOI  :  10.1016/0014-5793(94)00431-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Active transport of Fe³⁺ as ferrichrome complex through the outer membrane of Escherichia coli is mediated by the FhuA outer membrane protein and the TonB—ExbB—ExbD protein complex in the cytoplasmic membrane. The required energy is provided by the electrochemical potential of the cytoplasmic membrane which is assumed to induce a conformation of the TonB protein that causes a conformational change in FhuA so that bound ferrichrome is released into the periplasmic space located between the outer and the cytoplasmic membrane. Excision of segments as small as 12 amino acids in the largest surface loop of FhuA converted FhuA into an open channel through which ferrichrome and antibiotics diffused independent of TonB—ExbB—ExbD. It is proposed that FhuA forms a closed channel which is opened by movement of the gating loop through a kind of allosteric interaction with TonB. The gating loop is also involved in binding of all FhuA ligands which in addition to ferrichrome are the phages T1, T5, φ80, colicin M and the antibiotic albomycin.

【 授权许可】

Unknown