8UEE
Atomic structure of Salmonella SipA/F-actin complex by cryo-EM
Summary for 8UEE
| Entry DOI | 10.2210/pdb8uee/pdb |
| EMDB information | 42161 |
| Descriptor | Actin, alpha skeletal muscle, Cell invasion protein SipA, ADENOSINE-5'-DIPHOSPHATE, ... (6 entities in total) |
| Functional Keywords | actin, salmonella, type iii secretion system, sipa, cell invasion |
| Biological source | Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 More |
| Total number of polymer chains | 11 |
| Total formula weight | 410610.20 |
| Authors | Niedzialkowska, E.,Runyan, L.,Kudryashova, E.,Kudryashov, D.S.,Egelman, E.H. (deposition date: 2023-10-01, release date: 2023-12-27, Last modification date: 2024-07-10) |
| Primary citation | Niedzialkowska, E.,Runyan, L.A.,Kudryashova, E.,Egelman, E.H.,Kudryashov, D.S. Stabilization of F-actin by Salmonella effector SipA resembles the structural effects of inorganic phosphate and phalloidin. Structure, 32:725-738.e8, 2024 Cited by PubMed Abstract: Entry of Salmonella into host enterocytes relies on its pathogenicity island 1 effector SipA. We found that SipA binds to F-actin in a 1:2 stoichiometry with sub-nanomolar affinity. A cryo-EM reconstruction revealed that SipA's globular core binds at the groove between actin strands, whereas the extended C-terminal arm penetrates deeply into the inter-strand space, stabilizing F-actin from within. The unusually strong binding of SipA is achieved by a combination of fast association via the core and very slow dissociation dictated by the arm. Similar to P, BeF, and phalloidin, SipA potently inhibited actin depolymerization by actin depolymerizing factor (ADF)/cofilin, which correlated with increased filament stiffness, supporting the hypothesis that F-actin's mechanical properties contribute to the recognition of its nucleotide state by protein partners. The remarkably strong binding to F-actin maximizes the toxin's effects at the injection site while minimizing global influence on the cytoskeleton and preventing pathogen detection by the host cell. PubMed: 38518780DOI: 10.1016/j.str.2024.02.022 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (3.2 Å) |
Structure validation
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