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| Title | Structural insights into the secretin translocation channel in the type II secretion system. |
|---|---|
| Journal, issue, pages | Nat Struct Mol Biol, Vol. 24, Issue 2, Page 177-183, Year 2017 |
| Publish date | Jan 9, 2017 |
 Authors | Zhaofeng Yan / Meng Yin / Dandan Xu / Yongqun Zhu / Xueming Li /  |
| PubMed Abstract | The secretin GspD of the type II secretion system (T2SS) forms a channel across the outer membrane in Gram-negative bacteria to transport substrates from the periplasm to the extracellular milieu. ...The secretin GspD of the type II secretion system (T2SS) forms a channel across the outer membrane in Gram-negative bacteria to transport substrates from the periplasm to the extracellular milieu. The lack of an atomic-resolution structure of the GspD channel hinders the investigation of substrate translocation mechanism of T2SS. Here we report cryo-EM structures of two GspD channels (∼1 MDa), from Escherichia coli K12 and Vibrio cholerae, at ∼3 Å resolution. The structures reveal a pentadecameric channel architecture, wherein three rings of GspD N domains form the periplasmic channel. The secretin domain constitutes a novel double β-barrel channel, with at least 60 β-strands in each barrel, and is stabilized by S domains. The outer membrane channel is sealed by β-strand-enriched gates. On the basis of the partially open state captured, we proposed a detailed gate-opening mechanism. Our structures provide a structural basis for understanding the secretin superfamily and the mechanism of substrate translocation in T2SS. |
 External links | Nat Struct Mol Biol / PubMed:28067918 |
| Methods | EM (single particle) |
| Resolution | 3.04 - 4.22 Å |
| Structure data | EMDB-6675, PDB-5wq7: EMDB-6676, PDB-5wq8: EMDB-6677, PDB-5wq9:  EMDB-6678: |
| Source |
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 Keywords |  PROTEIN TRANSPORT / Secretin family / C15 symmetry / T2SS / Secretin / G453A mutant |
