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Title | Cryo-EM structure of the Agrobacterium tumefaciens T4SS-associated T-pilus reveals stoichiometric protein-phospholipid assembly. |
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Journal, issue, pages | Structure, Vol. 31, Issue 4, Page 385-394.e4, Year 2023 |
Publish date | Apr 6, 2023 |
Authors | Stefan Kreida / Akihiro Narita / Matthew D Johnson / Elitza I Tocheva / Anath Das / Debnath Ghosal / Grant J Jensen / |
PubMed Abstract | Agrobacterium tumefaciens causes crown gall disease in plants by the horizontal transfer of oncogenic DNA. The conjugation is mediated by the VirB/D4 type 4 secretion system (T4SS) that assembles an ...Agrobacterium tumefaciens causes crown gall disease in plants by the horizontal transfer of oncogenic DNA. The conjugation is mediated by the VirB/D4 type 4 secretion system (T4SS) that assembles an extracellular filament, the T-pilus, and is involved in mating pair formation between A. tumefaciens and the recipient plant cell. Here, we present a 3 Å cryoelectron microscopy (cryo-EM) structure of the T-pilus solved by helical reconstruction. Our structure reveals that the T-pilus is a stoichiometric assembly of the VirB2 major pilin and phosphatidylglycerol (PG) phospholipid with 5-start helical symmetry. We show that PG head groups and the positively charged Arg 91 residues of VirB2 protomers form extensive electrostatic interactions in the lumen of the T-pilus. Mutagenesis of Arg 91 abolished pilus formation. While our T-pilus structure is architecturally similar to previously published conjugative pili structures, the T-pilus lumen is narrower and positively charged, raising questions of whether the T-pilus is a conduit for ssDNA transfer. |
External links | Structure / PubMed:36870333 / PubMed Central |
Methods | EM (helical sym.) |
Resolution | 3.0 Å |
Structure data | EMDB-28957, PDB-8fai: |
Chemicals |
ChemComp-XL0: |
Source |
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Keywords | PROTEIN FIBRIL / VirB/D4 T4SS / Bacterial conjugation / T-pilus / helical filament |