5zfu

<StructureSection load='5zfu' size='340' side='right' caption='[[5zfu]], [[Resolution|resolution]] 6.70&Aring;' scene=''>

<table><tr><td colspan='2'>[[5zfu]] is a 9 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5ZFU OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5ZFU FirstGlance]. <br>

</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5zfu FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5zfu OCA], [http://pdbe.org/5zfu PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=5zfu RCSB], [http://www.ebi.ac.uk/pdbsum/5zfu PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=5zfu ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/EXBB_ECOLI EXBB_ECOLI]] Involved in the TonB-dependent energy-dependent transport of various receptor-bound substrates. Protects ExbD from proteolytic degradation and functionally stabilizes TonB. [[http://www.uniprot.org/uniprot/EXBD_ECOLI EXBD_ECOLI]] Involved in the TonB-dependent energy-dependent transport of various receptor-bound substrates.

Gram-negative bacteria import essential nutrients such as iron and vitamin B12 through outer membrane receptors. This process utilizes proton motive force harvested by the Ton system made up of three inner membrane proteins, ExbB, ExbD and TonB. ExbB and ExbD form the proton channel that energizes uptake through TonB. Recently, crystal structures suggest that the ExbB pentamer is the scaffold. Here, we present structures of hexameric complexes of ExbB and ExbD revealed by X-ray crystallography and single particle cryo-EM. Image analysis shows that hexameric and pentameric complexes coexist, with the proportion of hexamer increasing with pH. Channel current measurement and 2D crystallography support the existence and transition of the two oligomeric states in membranes. The hexameric complex consists of six ExbB subunits and three ExbD transmembrane helices enclosed within the central channel. We propose models for activation/inactivation associated with hexamer and pentamer formation and utilization of proton motive force.

 

== References ==

</StructureSection>

[[Category: Maki-Yonekura, S]]

[[Category: Matsuoka, R]]

[[Category: Yamashita, Y]]

[[Category: Yonekura, K]]

[[Category: Energizer]]

[[Category: Ion channel]]

[[Category: Proton motive force]]

[[Category: Transporter]]