8FAI

Cryo-EM structure of the Agrobacterium T-pilus

Summary for 8FAI

• Entry DOI: 10.2210/pdb8fai/pdb
• EMDB information: 28957
• Descriptor: Protein virB2, (7Z,19R,22S,25R)-22,25,26-trihydroxy-16,22-dioxo-17,21,23-trioxa-22lambda~5~-phosphahexacos-7-en-19-yl (9Z)-octadec-9-enoate (2 entities in total)
• Functional Keywords: virb/d4 t4ss, bacterial conjugation, t-pilus, helical filament, protein fibril
• Biological source: Agrobacterium tumefaciens
• Total number of polymer chains: 15
• Total formula weight: 196101.45

Authors

Kreida, S.,Narita, A.,Johnson, M.D.,Tocheva, E.I.,Das, A.,Jensen, G.J.,Ghosal, D. (deposition date: 2022-11-27, release date: 2024-03-13)

Primary citation

Kreida, S.,Narita, A.,Johnson, M.D.,Tocheva, E.I.,Das, A.,Ghosal, D.,Jensen, G.J.
Cryo-EM structure of the Agrobacterium tumefaciens T4SS-associated T-pilus reveals stoichiometric protein-phospholipid assembly.
Structure, 31:385-394.e4, 2023

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 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.

PubMed: 36870333
DOI: 10.1016/j.str.2023.02.005

Experimental method

ELECTRON MICROSCOPY (3 Å)