5NV9

Substrate-bound outward-open state of a Na+-coupled sialic acid symporter reveals a novel Na+-site

Summary for 5NV9

• Entry DOI: 10.2210/pdb5nv9/pdb
• Descriptor: Putative sodium:solute symporter, SODIUM ION, N-acetyl-beta-neuraminic acid, ... (6 entities in total)
• Functional Keywords: membrane protein, membrane symporter, sialic acid, outward-open, sodium-coupled
• Biological source: Proteus mirabilis (strain HI4320)
• Total number of polymer chains: 1
• Total formula weight: 55893.80

Authors

Wahlgren, W.Y.,North, R.A.,Dunevall, E.,Paz, A.,Goyal, P.,Bisignano, P.,Grabe, M.,Dobson, R.,Abramson, J.,Ramaswamy, S.,Friemann, R. (deposition date: 2017-05-03, release date: 2018-04-04, Last modification date: 2024-11-06)

Primary citation

Wahlgren, W.Y.,Dunevall, E.,North, R.A.,Paz, A.,Scalise, M.,Bisignano, P.,Bengtsson-Palme, J.,Goyal, P.,Claesson, E.,Caing-Carlsson, R.,Andersson, R.,Beis, K.,Nilsson, U.J.,Farewell, A.,Pochini, L.,Indiveri, C.,Grabe, M.,Dobson, R.C.J.,Abramson, J.,Ramaswamy, S.,Friemann, R.
Substrate-bound outward-open structure of a Na+-coupled sialic acid symporter reveals a new Na+site.
Nat Commun, 9:1753-1753, 2018

PubMed Abstract: Many pathogenic bacteria utilise sialic acids as an energy source or use them as an external coating to evade immune detection. As such, bacteria that colonise sialylated environments deploy specific transporters to mediate import of scavenged sialic acids. Here, we report a substrate-bound 1.95 Å resolution structure and subsequent characterisation of SiaT, a sialic acid transporter from Proteus mirabilis. SiaT is a secondary active transporter of the sodium solute symporter (SSS) family, which use Na gradients to drive the uptake of extracellular substrates. SiaT adopts the LeuT-fold and is in an outward-open conformation in complex with the sialic acid N-acetylneuraminic acid and two Na ions. One Na binds to the conserved Na2 site, while the second Na binds to a new position, termed Na3, which is conserved in many SSS family members. Functional and molecular dynamics studies validate the substrate-binding site and demonstrate that both Na sites regulate N-acetylneuraminic acid transport.

PubMed: 29717135
DOI: 10.1038/s41467-018-04045-7

Experimental method

X-RAY DIFFRACTION (1.95 Å)