Cryo-EM structure of the Agrobacterium tumefaciens T4SS-associated T-pilus reveals stoichiometric protein-phospholipid assembly

Stefan Kreida, Akihiro Narita, Matthew D. Johnson, Elitza I. Tocheva, Anath Das, Debnath Ghosal, Grant J. Jensen

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)385-394.e4
JournalStructure
Volume31
Issue number4
DOIs
StatePublished - Apr 6 2023

Bibliographical note

Publisher Copyright:
© 2023 Elsevier Ltd

Keywords

  • Agrobacterium tumefaciens
  • T-pilus
  • VirB/D4 T4SS
  • bacterial conjugation
  • cryo-EM
  • helical filament

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

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