H pilin cyclisation and pilus biogenesis are promiscuous but electrostatic perturbations impair conjugation efficiency.

ABSTRACT: During conjugation, plasmid DNA is transferred from donor to recipient bacteria via the plasmid-encoded mating pilus, formed as thin helical assemblies of polymerised pilin subunits. In the IncHI1 R27 plasmid-encoded pilus, the TrhA pilin undergoes cyclisation (via a peptide bond between Gly1 and Asp69), essential for conjugation. Gly1 and Asp69 are exposed on the pilus surface and conserved in all TrhA pilins in the Plascad database. Substituting Asp69 with Asn, Ala, Gly, or Arg did not prevent cyclisation or pilus formation, which remained structurally indistinguishable from the wild type. Conjugation efficiency of the Asp69 substitutions across multiple recipient species correlated with side chain size, in the order Asp69Asn > Asp69Ala > Asp69Gly. However, Asp69Arg, as well as Asp69Lys

SUBMITTER: He S 

PROVIDER: S-EPMC12667790 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature