Mechanistic Insights Revealed by YbtPQ in the Occluded State

• Published in: Biomolecules (Basel, Switzerland) Vol. 14; no. 3; p. 322
• Main Authors: Hu, Wenxin, Parkinson, Chance, Zheng, Hongjin
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01-03-2024; MDPI
• Subjects: ABC transporter; ABC transporters; Adenosine Triphosphate; ATP-Binding Cassette Transporters - metabolism; Biochemistry & Molecular Biology; Carrier proteins; Conformation; cryo-EM; Cryoelectron Microscopy; Dimerization; Electron microscopy; Escherichia coli; Exports; Lipids; Models, Molecular; Molecular biology; occluded; Physiological aspects; Protein Conformation; Siderophores (Microbiology); Transmembrane domains; Vanadate; Vanadates; yersiniabactin importer YbtPQ; United States; yersiniabactin importer YbtPQ; occluded; ABC transporter; cryo-EM
• ISSN: 2218-273X; 2218-273X
• DOI: 10.3390/biom14030322

Recently, several ATP-binding cassette (ABC) importers have been found to adopt the typical fold of type IV ABC exporters. Presumably, these importers would function under the transport scheme of "alternating access" like those exporters, cycling through inward-open, occluded, and outward-open conformations. Understanding how the exporter-like importers move substrates in the opposite direction requires structural studies on all the major conformations. To shed light on this, here we report the structure of yersiniabactin importer YbtPQ from uropathogenic
in the occluded conformation trapped by ADP-vanadate (ADP-Vi) at a 3.1 Å resolution determined by cryo-electron microscopy. The structure shows unusual local rearrangements in multiple helices and loops in its transmembrane domains (TMDs). In addition, the dimerization of the nucleotide-binding domains (NBDs) promoted by the vanadate trapping is highlighted by the "screwdriver" action at one of the two hinge points. These structural observations are rare and thus provide valuable information to understand the structural plasticity of the exporter-like ABC importers.