| Title: |
Structural and biophysical analysis of a Haemophilus influenzae tripartite ATP-independent periplasmic (TRAP) transporter |
| Authors: |
Currie, MJ; Davies, JS; Scalise, M; Gulati, A; Wright, JD; Newton-Vesty, MC; Abeysekera, GS; Subramanian, R; Wahlgren, WY; Friemann, R; Allison, JR; Mace, PD; Griffin, MDW; Demeler, B; Wakatsuki, S; Drew, D; Indiveri, C; Dobson, RCJ; North, RA |
| Publisher Information: |
eLife Sciences Publications, Ltd |
| Publication Year: |
2024 |
| Collection: |
The University of Melbourne: Digital Repository |
| Description: |
Tripartite ATP-independent periplasmic (TRAP) transporters are secondary-active transporters that receive their substrates via a soluble-binding protein to move bioorganic acids across bacterial or archaeal cell membranes. Recent cryo-electron microscopy (cryo-EM) structures of TRAP transporters provide a broad framework to understand how they work, but the mechanistic details of transport are not yet defined. Here we report the cryo-EM structure of the Haemophilus influenzae N -acetylneuraminate TRAP transporter ( Hi SiaQM) at 2.99 Å resolution (extending to 2.2 Å at the core), revealing new features. The improved resolution (the previous Hi SiaQM structure is 4.7 Å resolution) permits accurate assignment of two Na + sites and the architecture of the substrate-binding site, consistent with mutagenic and functional data. Moreover, rather than a monomer, the Hi SiaQM structure is a homodimer. We observe lipids at the dimer interface, as well as a lipid trapped within the fusion that links the SiaQ and SiaM subunits. We show that the affinity ( K D ) for the complex between the soluble Hi SiaP protein and Hi SiaQM is in the micromolar range and that a related SiaP can bind Hi SiaQM. This work provides key data that enhances our understanding of the ‘elevator-with-an-operator’ mechanism of TRAP transporters. |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| ISSN: |
2050-084X |
| Relation: |
https://hdl.handle.net/11343/348477 |
| Availability: |
https://hdl.handle.net/11343/348477 |
| Rights: |
https://creativecommons.org/licenses/cc-by/4.0 ; cc-by |
| Accession Number: |
edsbas.4324F17B |
| Database: |
BASE |