8OYF

Crystal structure of ASBTNM in lipidic cubic phase without substrate bound

Summary for 8OYF

• Entry DOI: 10.2210/pdb8oyf/pdb
• Descriptor: Transporter, SODIUM ION, PHOSPHATIDYLETHANOLAMINE, ... (7 entities in total)
• Functional Keywords: secondary membrane transporter, transport protein
• Biological source: Neisseria meningitidis MC58
• Total number of polymer chains: 1
• Total formula weight: 35937.08

Authors

Becker, P.,Cameron, A.D. (deposition date: 2023-05-04, release date: 2023-07-12, Last modification date: 2023-09-13)

Primary citation

Becker, P.,Naughton, F.B.,Brotherton, D.H.,Pacheco-Gomez, R.,Beckstein, O.,Cameron, A.D.
Mechanism of substrate binding and transport in BASS transporters.
Biorxiv, 2023

PubMed Abstract: The Bile Acid Sodium Symporter (BASS) family transports a wide array of molecules across membranes, including bile acids in humans, and small metabolites in plants. These transporters, many of which are sodium-coupled, have been shown to use an elevator mechanism of transport, but exactly how substrate binding is coupled to sodium ion binding and transport is not clear. Here we solve the crystal structure at 2.3 Å of a transporter from (ASBT) in complex with pantoate, a potential substrate of ASBT. The BASS family is characterised by two helices that cross-over in the centre of the protein in an arrangement that is intricately held together by two sodium ions. We observe that the pantoate binds, specifically, between the N-termini of two of the opposing helices in this cross-over region. During molecular dynamics simulations the pantoate remains in this position when sodium ions are present but is more mobile in their absence. Comparison of structures in the presence and absence of pantoate demonstrates that pantoate elicits a conformational change in one of the cross-over helices. This modifies the interface between the two domains that move relative to one another to elicit the elevator mechanism. These results have implications, not only for ASBT but for the BASS family as a whole and indeed other transporters that work through the elevator mechanism.

PubMed: 37645971
DOI: 10.1101/2023.06.02.543391

Experimental method

X-RAY DIFFRACTION (2.1 Å)