9FXC
Cryo-EM structure of IrtAB in inward-facing state in nanodisc
Summary for 9FXC
| Entry DOI | 10.2210/pdb9fxc/pdb |
| Related | 6TEJ |
| EMDB information | 10319 50848 |
| Descriptor | Mycobactin import ATP-binding/permease protein IrtA, Mycobactin import ATP-binding/permease protein IrtB, PHOSPHOTHIOPHOSPHORIC ACID-ADENYLATE ESTER (3 entities in total) |
| Functional Keywords | abc transporter, type iv abc importer siderophore, mycobactin, heterodimeric abc transporter, membrane protein |
| Biological source | Mycolicibacterium thermoresistibile ATCC 19527 More |
| Total number of polymer chains | 2 |
| Total formula weight | 160102.57 |
| Authors | Gonda, I.,Seeger, M.A. (deposition date: 2024-07-01, release date: 2024-12-18, Last modification date: 2025-02-12) |
| Primary citation | Gonda, I.,Sorrentino, S.,Galazzo, L.,Lichti, N.P.,Arnold, F.M.,Mehdipour, A.R.,Bordignon, E.,Seeger, M.A. The mycobacterial ABC transporter IrtAB employs a membrane-facing crevice for siderophore-mediated iron uptake. Nat Commun, 16:1133-1133, 2025 Cited by PubMed Abstract: The mycobacterial ABC transporter IrtAB features an ABC exporter fold, yet it imports iron-charged siderophores called mycobactins. Here, we present extensive cryo-EM analyses and DEER measurements, revealing that IrtAB alternates between an inward-facing and an outward-occluded conformation, but does not sample an outward-facing conformation. When IrtAB is locked in its outward-occluded conformation in nanodiscs, mycobactin is bound in the middle of the lipid bilayer at a membrane-facing crevice opening at the heterodimeric interface. Mutations introduced at the crevice abrogate mycobactin import and in corresponding structures, the crevice is collapsed. A conserved triple histidine motif coordinating a zinc ion is present below the mycobactin binding site. Substitution of these histidine residues with alanine results in a decoupled transporter, which hydrolyzes ATP, but lost its capacity to import mycobactins. Our data suggest that IrtAB imports mycobactin via a credit-card mechanism in a transport cycle that is coupled to the presence of zinc. PubMed: 39880813DOI: 10.1038/s41467-024-55136-7 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (3.6 Å) |
Structure validation
Download full validation report
