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| Title | The hemolysin A secretion system is a multi-engine pump containing three ABC transporters. |
|---|---|
| Journal, issue, pages | Cell, Vol. 185, Issue 18, Page 3329-3340.e13, Year 2022 |
| Publish date | Sep 1, 2022 |
 Authors | Hongtu Zhao / James Lee / Jue Chen /  |
| PubMed Abstract | Type 1 secretion systems (T1SSs) are widespread in pathogenic Gram-negative bacteria, extruding protein substrates following synthesis of the entire polypeptide. The Escherichia coli hemolysin A ...Type 1 secretion systems (T1SSs) are widespread in pathogenic Gram-negative bacteria, extruding protein substrates following synthesis of the entire polypeptide. The Escherichia coli hemolysin A secretion system has long been considered a prototype in structural and mechanistic studies of T1SSs. Three membrane proteins-an inner membrane ABC transporter HlyB, an adaptor protein HlyD, and an outer membrane porin TolC-are required for secretion. However, the stoichiometry and structure of the complex are unknown. Here, cryo-electron microscopy (cryo-EM) structures determined in two conformations reveal that the inner membrane complex is a hetero-dodecameric assembly comprising three HlyB homodimers and six HlyD subunits. Functional studies indicate that oligomerization of HlyB and HlyD is essential for protein secretion and that polypeptides translocate through a canonical ABC transporter pathway in HlyB. Our data suggest that T1SSs entail three ABC transporters, one that functions as a protein channel and two that allosterically power the translocation process. |
 External links | Cell / PubMed:36055198 |
| Methods | EM (single particle) |
| Resolution | 2.9 - 3.4 Å |
| Structure data | EMDB-25116, PDB-7sgr: EMDB-27326, PDB-8dck: |
| Chemicals |  ChemComp-6OU:  ChemComp-ATP:  ChemComp-MG: |
| Source |
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 Keywords | MEMBRANE PROTEIN / hydrolase / transport |
Escherichia coli O6:H1 (bacteria)