5ZFP

Structure of the ExbB/ExbD hexameric complex

Summary for 5ZFP

• Entry DOI: 10.2210/pdb5zfp/pdb
• Descriptor: Biopolymer transport protein ExbB (2 entities in total)
• Functional Keywords: ton system, ion channel, energizer, transporter, proton motive force, transport protein
• Biological source: Escherichia coli (strain K12)
• Cellular location: Cell inner membrane; Multi-pass membrane protein: P0ABU7
• Total number of polymer chains: 12
• Total formula weight: 315747.86

Authors

Maki-Yonekura, S.,Matsuoka, R.,Yonekura, K. (deposition date: 2018-03-06, release date: 2018-05-09, Last modification date: 2023-11-22)

Primary citation

Maki-Yonekura, S.,Matsuoka, R.,Yamashita, Y.,Shimizu, H.,Tanaka, M.,Iwabuki, F.,Yonekura, K.
Hexameric and pentameric complexes of the ExbBD energizer in the Ton system.
Elife, 7:-, 2018

PubMed Abstract: Gram-negative bacteria import essential nutrients such as iron and vitamin B 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.

PubMed: 29661272
DOI: 10.7554/eLife.35419

Experimental method

X-RAY DIFFRACTION (2.84 Å)